Mushroom bruschetta is such a chic and gourmet-looking offering for cocktail parties and gatherings, but it's so easy to make! Bake the crostini ahead of time and store in an air-tight container for up to a day. The assembled bruschetta can be served warm, but will hold up for about an hour at room temperature.
Heat the oven to 375°F. Slice the baguette into 24 ½” slices and spread evenly over a baking sheet. Brush each side with olive oil (about 2 tablespoons total), then sprinkle a bit of salt over each piece (about ½ teaspoon total).
Transfer the baking sheet to the oven and bake until the crostini are golden brown, flipping once halfway through, 10-12 minutes. Remove from the oven and set aside until you're ready to assemble. If making the crostini in advance, allow to cool, then place into a sealed container for up to 1 day.
Heat the butter and remaining two tablespoons of olive oil in a 12” skillet over medium high heat until the butter melts, then foams. Add mushrooms and toss to coat in the fat. Saute, stirring occasionally, until the mushrooms have released their liquids, the liquids have evaporated, and the edges are browned and crispy, about 15 minutes.
Add the garlic and rosemary and sautee, stirring frequently, until fragrant, 2-3 minutes. Pour in the white wine to deglaze the plan - cook, stirring frequently, until the liquid is absorbed. Season with the remaining ½ teaspoon salt and pepper, then remove from heat.
Assemble the bruschetta. Spread a teaspoon of ricotta cheese over the crostini then top with a tablespoon of sautéed mushrooms. Serve warm, right away, or set out at room temperature for up to one hour. Enjoy!