Very easy with store bought croissants. You can also use the same idea to make sweet filled croissants.
4 store bought croissants
2cups cream, half-and-half or milk
1sprig thyme, optional
1clove garlic, optional
3eggs plus 2 yolks
½ tsp salt
½ cup grated semihard cheese, like Gruyère, Comté or Emmenthal
½ cup grated Parmesan
Crumbled cooked bacon, optional
Carefully cut the rolls in half by slicing lengthwise the top portion. Make a well in the center of the croissant but be careful to keep a wall of dough. These things will leak anyway but try to keep it as complete as possible. You are essentially making a very delicate bread bowl.
Put cream in a small pot with thyme and garlic, if you're using them. Cook just until it begins to steam. Heat oven to 375 degrees.
Put eggs, cayenne and salt in a medium bowl and whisk or beat until blended; stir in the cheese. Remove thyme and garlic from cream, then add cream gradually to egg mixture, whisking constantly. Gently cook until thickened. Put parchment paper or aluminum foil in the bottom of a baking sheet. Spray lightly with cooking spray. Place the croissants on the tray. Pour mixture carefully into the bread bowls.
Place in oven and bake for 25 - 30 minutes or until the mixture is firm but still a bit jiggly. Top with crumbled bacon and serve.