Preheat oven to 400°F. Grease a 24‑cavity mini muffin tin and set aside.

Unwrap the thawed puff pastry sheet and place it on a clean work surface. Use a rolling pin to roll it into a 10" x 15" rectangle.

Cut the rectangle into 4 strips one direction and 6 strips the other to make 24 equal squares.

Press one pastry square into each muffin cavity, forming a small cup with the edges slightly up.

Using a sharp knife, cut the 4 oz. brie round into 24 pieces (about 3/4" each). You may leave the rind on if you like.

Place one piece of brie into the center of each pastry cup.

Top each brie piece with 1 teaspoon of whole berry cranberry sauce (use the 1/2 cup total).

Evenly divide the 1/2 cup chopped walnuts over the 24 bites and sprinkle the tops with coarse sea salt.

Bake for 18–20 minutes, or until the puff pastry is puffed and golden brown.

Let the bites cool in the pan for a few minutes, then remove and serve warm.