These crostini provide guests with a delicious vegetarian option—caramelized onions, sautéed mushrooms, and herbed goat cheese. A savory and sweet combination of vegetables on top of a creamy spread and crunchy bread will disappear fast! It’s a great option when you want to make plenty of servings with minimal effort. Plus, the topping options are endless. You can even prepare the components ahead of time, and assemble, serve, and enjoy whenever you want.
Toasting the Bread for Crostini
This is a two- to three-bite handheld starter. Slender baguettes are my top choice—they hold up well after toasting and have a light and crisp texture. Slice them about 1/2-inch thick and brush a high-quality extra virgin olive oil on both sides. The oil crisps the bread when baked and adds a nice earthy and fruity flavor. It only takes about ten minutes to toast. The surface should be lightly browned but not completely dried out and brittle like croutons.
Why Caramelize Onions?
I like to caramelize the onions for a layer of flavor on the crostini. I add a small amount of brown sugar to kickstart the process of caramelizing the onions in olive oil and butter. With a little bit of patience, the onions will soften, turn translucent, and then golden in color. The natural sugars in the vegetable come to the surface, adding a subtle sweetness. This extra effort makes a big flavor impact!
The Mushrooms
Brown mushrooms like cremini or baby bella are great for cooking because they hold their shape well, instead of shrinking into tiny pieces. I sauté them to concentrate their earthy, savory flavor. Add a small amount of soy sauce to make the mushroom’s flavor stronger. A splash of balsamic vinegar adds some acidity, which brightens the mushrooms and provides a hint of sweetness.
Make a Creamy Goat Cheese Spread
To complement the tender slices of mushrooms and caramelized onions, make a tangy and creamy goat cheese spread. I like to keep this simple to not take away from the vegetable topping. It has four ingredients: soft goat cheese, freshly chopped chives, and onion and garlic powder. That’s it! This also makes a nice dip for crackers, or I like to add some on top of soft scrambled eggs for breakfast.
How to Assemble the Crostini
Right before you’re ready to serve the crostini, shmear a thin layer of the goat cheese spread on top of the toast. The cheese also creates a barrier, so the toast doesn’t get soggy. Add some of the warm mushrooms and onions on top, and garnish with freshly cracked black pepper and chopped chives. The toast tastes the best when enjoyed within an hour of topping.
Ingredient Swaps and Substitutions
If you want to switch up the flavor profile of the crostini, try these mushroom, cheese, and herb options.
Use a mixture of mushrooms like brown, white, and dried porcini for a variety of mushroom flavors.Goat cheese can be swapped for cream cheese, whipped feta, or mascarpone.Add other fresh herbs to the cheese spread like chopped dill, basil, parsley, or oregano.
Storage Instructions
The toasts can be made up to five days in advance. Store them in an airtight container and leave them on the counter. You can freeze them for up to one month. Let them defrost on the kitchen counter before topping. The crostini can be assembled up to two hours ahead of time and refrigerated until ready to serve. However, don’t wait any longer or the toast will turn soft!
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Bake until dry, lightly browned, and crisp, about 10 minutes. Flip the bread over halfway through baking. Cool on the baking sheet. Cook, stirring frequently, until the onions begin to soften and lightly brown, about 5 minutes. Reduce the heat to medium heat, and cook the onions, stirring frequently, until caramelized, 10 to 12 minutes. Add the garlic and sauté until fragrant, about 30 seconds. Add the balsamic vinegar, soy sauce, the remaining 1/4 teaspoon salt, and black pepper. Sauté for 1 minute. Season to taste with more salt and pepper. Set aside. Top each with about 2 tablespoons of the caramelized onion and mushroom mixture. Sprinkle with black pepper and more chives, if you’d like. Arrange the crostini on a platter and serve.
