01 - Preheat oven to 400°F and lightly grease a 24-cup mini muffin tin or line with mini paper liners.
02 - On a lightly floured work surface, roll the puff pastry into a 12x12 inch square and cut into 24 equal squares.
03 - Gently press each pastry square into a well of the mini muffin tin, leaving the corners upright.
04 - Place a cube of Brie cheese in each pastry cup. Spoon 1 teaspoon of cranberry sauce over the Brie in each well.
05 - Sprinkle each bite with chopped rosemary, thyme, and toasted pecans or walnuts, if desired.
06 - Brush the exposed pastry corners with beaten egg using a pastry brush for a glossy finish.
07 - Bake in the preheated oven for 15 to 20 minutes, or until the pastry is puffed and golden brown.
08 - Let bites cool in the tin for 5 minutes, then transfer to a wire rack. Serve warm.