Heat oven to 350 degrees F.
- Place bread on baking sheet and cook until lightly browned, about 10 minutes. Set aside.
- Meanwhile, in a large skillet over medium high heat, cook bacon until crisp and browned about 5 minutes. Add shallots and cook until softened about 4 minutes. Add mushrooms and cook until softened about 3 minutes longer. Add a tablespoon of water if the pan gets to dry at any point in the cooking. Set aside.
- Meanwhile, in a small bowl, combine yogurt, olive oil, salt and pepper. Spread mixture on top of crostini and top with bacon mixture and place back on the baking pan. Return to oven to warm the yogurt topping, about 4 minutes. Serve warm.