For the crostini:
24 thin slices baguette or other crusty bread
1-2 cloves garlic, halved
For the mushroom spread:
3-4 tbsp. olive oil, divided
1 lb. mushrooms, any combination, roughly chopped
2-3 cloves garlic, minced
1 tbsp. fresh parsley, minced
2 tsp. fresh thyme leaves
½ tsp. fresh rosemary, minced
1 tsp. coarse salt
Freshly ground pepper, to taste
Preheat the oven to 350˚ F. To make the crostini, place baguette slices in a single layer on a baking sheet. Lightly brush each slice of bread with olive oil. Bake 15-20 minutes, until golden and crisp. Once the bread slices have cooled enough to handle, rub each crostini with the cut side of a garlic clove. Set aside.
To make the mushroom spread, heat 1 tablespoon of the olive oil in a large skillet over medium-high heat. Add the chopped mushrooms and cook, stirring occasionally, until lightly browned and almost all of the liquid has evaporated, about 10 minutes. Mix in the garlic, parsley, thyme, rosemary and salt, cooking 1-2 more minutes, until fragrant.
Transfer the mixture to a food processor with the feed tube open to vent steam. Process until finely ground. With the processor running, add the remaining 2-3 tablespoons of olive oil, until the mixture is smooth and spreadable. Adjust seasoning with salt and pepper to taste.
Spread each piece of bread with a thin layer of the mushroom mixture, transfer to a platter and serve.