Name: Caramelized Onion and Blue Cheese Crostini Recipe
Prep time: 15 min
Cook time: 1 h 10 min
Total time: 1 h 25 min
Cuisine: American
Ingredients: 1 large vidalia onion (about 12 oz), peeled, halved, and thinly sliced; 2 tablespoons extra-virgin olive oil; ¼ teaspoon kosher salt; 2 teaspoons balsamic vinegar; 1 baguette, sliced into ¼-inch rounds; ⅓ cup fig preserves; ¼ cup blue cheese crumbles; 2 sprigs fresh rosemary, torn or roughly chopped; Freshly ground black pepper, for serving

Jump to Recipe· 4.5 from 24 reviews

If you’re anything like me, you love those little bites that pack bold flavors and a bit of elegance — and that’s exactly why this Caramelized Onion and Blue Cheese Crostini Recipe should be your next kitchen adventure. The sweet, jammy onions paired with tangy blue cheese and a hint of fig jam create a mouthwatering combo that’s just perfect for entertaining or a fancy snack night in. Plus, I’m sharing all my tips to get those onions caramelized to perfection every time — you’re going to love how effortless and fantastic this recipe turns out.

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Why This Recipe Works

Balance of Flavors: The sweetness of caramelized onions and fig jam contrasts beautifully with the sharp, creamy blue cheese.
Simple Ingredients: Uses pantry staples and fresh produce you can easily find, making it accessible and fuss-free.
Versatile and Elegant: Perfect for casual gatherings or special occasions, this crostini never fails to impress guests.
Step-by-Step Friendly: Detailed steps help you master caramelizing onions without frustration.

Caramelized Onion and Blue Cheese Crostini, caramelized onion crostini with blue cheese, easy appetizer recipes, sophisticated finger foods, gourmet snack ideas - There is a white baking tray with twelve toasted slices of bread arranged in three rows of four. Each slice has a layer of dark caramelized onions topped with crumbled creamy blue cheese that is white with blue veins. To the right of the tray, there are some plain slices of bread showing a soft, light inside. Above the tray, a black cast iron pan holds more caramelized onions with a silver fork resting inside. On the left side, a wedge of blue cheese and sprigs of fresh herbs sit on the white marbled surface. Below this, a small white bowl contains more blue cheese crumbles, next to a glass jar of dark honey with a spoon inside. Photo taken with an iphone --ar 2:3 --v 7

Ingredients & Why They Work

Each ingredient in this Caramelized Onion and Blue Cheese Crostini Recipe plays a starring role, bringing layers of flavor and texture that build on each other beautifully. When you pick quality items, like a sweet Vidalia onion and creamy blue cheese, it makes all the difference. Here are a few insights to keep in mind while shopping!

Vidalia onion: This sweet onion caramelizes beautifully, giving you those rich, jammy notes that form the base of the crostini.
Extra-virgin olive oil: Adds a subtle fruity flavor and helps create that luscious texture when cooking onions.
Kosher salt: Enhances the onion’s natural sweetness without overpowering.
Balsamic vinegar: A splash at the end amps up depth and adds a subtle tangy-sweet finish.
Baguette: Thinly sliced rounds toast up crisp and provide the perfect crunchy canvas.
Fig preserves: Infuse subtle fruity sweetness that complements the cheese and onions.
Blue cheese crumbles: Their boldness contrasts lovely with the sweetness for a luxurious bite.
Fresh rosemary: Adds a fragrant herbal note that brightens every mouthful.
Freshly ground black pepper: A pinch rounds things out with mild heat.

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Note: You’ll find the complete list of ingredients, along with their exact measurements, in the printable recipe card at the bottom of this post.

Tweak to Your Taste

One of the best parts about this Caramelized Onion and Blue Cheese Crostini Recipe is how easy it is to make your own. I often switch up toppings or try different cheeses depending on what I have in the fridge. Feel free to play around with it until it feels totally you!

Cheese Swap: Sometimes I swap blue cheese for goat cheese for a milder tang that still packs character.
Add Nuts: Toasted walnuts or pecans add a wonderful crunch and pair amazingly with the fig preserves.
Herb Choices: Rosemary is my favorite, but thyme or fresh sage bring their own lovely twist.
Sweetener Variations: Try a honey drizzle instead of fig jam for a different spin on sweetness.

Step-by-Step: How I Make Caramelized Onion and Blue Cheese Crostini Recipe

Step 1: Slowly Caramelize the Onions

I can’t stress enough how much patience pays off here. Start by heating extra-virgin olive oil in a heavy skillet over medium-high heat, then add your thinly sliced Vidalia onions sprinkled with kosher salt. For the first 5 minutes, stir gently as the onions soften but try not to brown them yet. Then, turn the heat down to medium-low, cover with a lid, and cook slowly, stirring every 10-15 minutes. This slow process takes about an hour but transforms the onions into sweet, golden, jammy magic. If the onions ever seem like they’re sticking or browning too fast, splash a little water or broth in to deglaze and scrape up those flavor-packed bits from the pan.

Step 2: Add a Splash of Balsamic Vinegar

About 10 minutes before the onions finish cooking, stir in the balsamic vinegar. This addition deepens their flavor and balances the sweetness with a subtle tang. When the onions are perfectly caramelized and glossy, remove the pan from heat and set aside to cool while you prepare the rest.

Step 3: Prep and Toast Your Baguette Slices

Preheat your oven to 400°F (200°C) and arrange baguette slices on a baking sheet lined with parchment paper or foil for easy cleanup. Toast them in the oven for a few minutes until just crisp, but not too dry — you’ll want them sturdy enough to hold toppings while still a bit tender on the inside.

Step 4: Build Your Crostini

Spread 1 to 2 teaspoons of fig preserves on each toasted baguette round. Then, pile on a spoonful of your luscious caramelized onions, followed by a generous crumble of blue cheese. Slide the crostini back into the oven for about 4-5 minutes — just enough to soften the cheese and warm everything through without melting it away.

Step 5: Final Touches Before Serving

Once out of the oven, sprinkle each crostini with fresh rosemary and a few grinds of black pepper. This herbaceous note and mild pepper heat take each bite to the next level. Serve these at your next gathering, and I guarantee your friends will be asking for the recipe.

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Pro Tips for Making Caramelized Onion and Blue Cheese Crostini Recipe

Low and Slow Is Key: Don’t rush the onions by turning up the heat—slow caramelization means rich, sweet flavor without burning.
Watch Your Onions: Stir every 10-15 minutes to keep them from sticking or browning unevenly.
Toast the Bread Just Right: Crisp edges with a soft center keep the crostini satisfying without being too hard to bite.
Don’t Overdo the Cheese: Blue cheese is bold—you want enough to shine, but not to overpower the delicate fig and onions.

How to Serve Caramelized Onion and Blue Cheese Crostini Recipe

Garnishes

I love to top these crostini with fresh rosemary because its piney aroma cuts through the richness of the cheese and onions beautifully. Sometimes I add a quick drizzle of honey on top for a glossy, sweet finish that wows guests every time. Fresh cracked black pepper is my everyday go-to—never underestimate the magic of just a few twists.

Side Dishes

These crostini pair wonderfully with a crisp green salad—something with a bright vinaigrette to contrast the richness. I’ve also served them alongside a charcuterie board with olives, nuts, and cured meats for a lovely spread. If you’re enjoying wine, a glass of chilled Sauvignon Blanc or a fruity Pinot Noir complements the flavors beautifully.

Creative Ways to Present

For special occasions, I like arranging these crostini on a rustic wooden board with edible flowers for a pop of color and elegance. Another favorite is serving them in individual small plates with a sprig of rosemary each—makes your guests feel extra special and adds a fun presentation flair.

Make Ahead and Storage

Storing Leftovers

I usually store leftover caramelized onions in an airtight container in the fridge for up to 4-5 days, which makes for a fantastic quick topping later. Toasted crostini are best eaten fresh, but you can keep them in a sealed container for 1-2 days if needed—just expect they might soften a bit.

Freezing

I’ve found caramelized onions freeze well—just pop them in a freezer-safe bag or container for up to 3 months. I don’t recommend freezing the assembled crostini though, since the bread gets soggy. Instead, freeze onions separately and toast fresh baguette slices when you’re ready to serve.

Reheating

To reheat caramelized onions, I warm them gently in a skillet or microwave until heated through. If you’re reheating leftovers topped on bread, low oven heat helps maintain crispness without making the bread tough. Just keep an eye on them so the cheese warms but doesn’t melt away completely.

FAQs

Can I use other types of onions for this recipe?

Absolutely! While Vidalia onions are preferred for their sweetness and mild flavor, yellow or sweet Spanish onions also work well. Just note that more pungent onions might need a bit more cooking time to mellow out.
How do I prevent the onions from burning during caramelization?

Keep the heat low after the initial softening stage and stir regularly. If you see any browning or sticking on the pan’s bottom, add a splash of water or broth to loosen those bits and prevent burning. This deglazing is key for deep flavor without bitterness.
Can I make this recipe vegan or dairy-free?

Yes! Simply replace the blue cheese with a vegan blue cheese alternative or a tangy nut-based cheese spread. The rest of the recipe remains the same and still tastes amazing.
Is there an easy way to speed up caramelizing onions?

While you can increase heat slightly to speed it up, you risk uneven cooking and burnt bits. I recommend patience and slow cooking for the best flavor and texture, but if you’re short on time, slicing onions thinner can help them cook faster.
What kind of wine pairs well with these crostini?

A crisp white like Sauvignon Blanc or a fruity, light-bodied Pinot Noir pairs beautifully. These wines balance the richness of blue cheese and sweetness of caramelized onions without overpowering them.

Final Thoughts

This Caramelized Onion and Blue Cheese Crostini Recipe holds a special place in my kitchen because it’s simple yet so deeply satisfying—whether it’s a quiet night at home or a lively dinner with friends. If you’ve ever hesitated about tackling caramelized onions, trust me, the step-by-step method here will have you loving the process as much as the delicious results. Give it a try, and I promise you’ll be adding this to your regular entertaining arsenal in no time.