1. Preheat oven to 350°F. Slice the baguette into thin slices and line the pieces of bread on a baking sheet. Drizzle olive oil on the bread pieces and top with salt and pepper. Bake for 10-12 minutes until golden brown. When they come out of the oven rub one half of a garlic clove on the top of each crostini for more garlic flavor.
2. While the crostini are baking, stir together the Greek yogurt and mascarpone cheese with a rubber spatula until well incorporated.
3. Stir in the Gruyere and Swiss cheese and season with the Old Bay, salt, and black pepper.
4. Once all of the seasonings are combined, gently fold in the pieces of lump crab meat.
5. Gently spread the mixture into a pie plate or baking dish and bake for 40 minutes on 325°F.
6. Let stand for 5-10 minutes and serve immediately.