Heat the oven to 400F and grease a 24-cup mini muffin tin.
Unfold the cold pastry on a lightly floured counter and cut it into 24 squares. Work quickly; puff pastry that warms up stops puffing and turns greasy.
Press one square into each cup, letting the corners stick up. Brush the exposed corners with the egg wash.
Put a cube of brie in each cup, then top with about half a teaspoon of jam. Do not overfill or it will bubble over and weld to the pan.
Bake 16 to 18 minutes until deeply golden and puffed. Press a fresh raspberry into each while still hot, then finish with almonds, thyme, and flaky salt. Cool 5 minutes before lifting them out.