1teaspoonflaky sea saltsuch as Maldon or fleur de sel
1/2cupfinely chopped raw pecans
4springs fresh rosemarycut into 6 pieces
Position oven racks in the upper and lower thirds of the oven and preheat the oven to 375 degrees F. Place the Brie in the freezer for 15 minutes to firm up. VERY generously coat 2, 24-cup mini muffin pans with nonstick spray (if you only have 1 pan or if you have 2, 12-cups pans, make the Brie bites in batches).
Unroll 1 sheet puff pastry on a lightly floured work surface (leave the second sheet in the refrigerator until you are ready to use it). Roll into a 10 x 14-inch rectangle. Cut the sheet lengthwise into 4 even strips. Cut crosswise into 6 even strips. You will have 24 squares total (each square will be about 2 1/2 inches on each side). Gently separate the squares and press them into the mini muffin tins to create a puff pastry cup. With the tines of a fork, prick the bottom of each puff pastry in 2 to 3 places.
Cut the piece of Brie in half, then place 1 half back in the freezer. Dice the remaining Brie into 24 pieces (they will be between 3/4 and 1/2-inch on each side). Place one piece of Brie in the center of each mini muffin cup. Top each piece of Brie with 1 teaspoon cranberry sauce. Sprinkle with 1/2 teaspoon salt, then half of the chopped pecans. Place in the refrigerator. Repeat with the second sheet of puff pastry, second half of Brie, and the remaining salt and pecans.
Place each muffin pan on a rimmed baking sheet to catch any cheese or cranberry that bubbles over. Bake the pans on the upper and lower thirds of the oven for 18 to 20 minutes, until the pastry is puffed and the corners are golden brown, switching the pans' positions on the upper and lower racks once halfway through. Let cool in the pans for 3 minutes. If any of the Brie or cranberry has bubbled out, use a fork to scoot it back into the center of the bites (no one will know!).
Gently transfer the bites to a serving plate (I find a fork works well to transfer them). Garnish each with a small piece of fresh rosemary. Enjoy hot or at room temperature.
TO STORE: Store leftovers in an airtight storage container in the refrigerator for up to 3 days.
TO REHEAT: Place bites in a mini muffin tin and bake at 350 degrees F until warmed through. You can also serve these bites at room temperature.
TO FREEZE: Bake the Brie bites as directed and let cool completely. Then arrange the bites in a single layer on a baking sheet, and place in the freezer until solid. Store the frozen bites in a single layer in an airtight freezer-safe storage container or ziptop bag for up to 2 months. Reheat from frozen in a 350 degree F oven until hot.
TO MAKE AHEAD: Fully assemble the bites in the muffin pan, and refrigerate them unbaked for up to 3 days before baking. You can also fully bake and freeze these bites for up to 2 months. See notes on this above.