2 sheets of frozen puff pastry thawed overnight in the refrigerator
8 ounces Brie cheese
1 cup homemade cranberry sauce or whole-berry cranberry sauce
1 teaspoon flaky sea salt
1/2 cup finely chopped raw pecans
4 sprigs fresh rosemary, cut into 6 pieces
Preheat the oven to 375 degrees F.
Place the Brie in the freezer for 15 minutes to firm up.
Very generously coat two 24-cup mini muffin pans with nonstick spray (if you only have one pan or if you have two 12-cup pans, make the Brie bites in batches).
Unroll one sheet of 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 10x14-inch rectangle. Cut the sheet lengthwise into four even strips. Cut crosswise into six even strips. You will have 24 squares in total. 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 two to three places.
Cut the piece of Brie in half, then place one 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 of 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, the second half of the 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 three minutes. If any of the Brie or cranberry has bubbled out, use a fork to scoot it back into the center of the bites.
Gently transfer the bites to a serving plate. Garnish each with a small piece of fresh rosemary. Enjoy hot or at room temperature.