Step 1: Preheat your oven to 400°F (200°C). Lightly grease a 24-cup mini muffin tin or line with paper liners.
Step 2: On a lightly floured surface, gently unroll the thawed puff pastry sheet. Using a pizza cutter or sharp knife, cut the pastry into 24 equal squares (approximately 2x2 inches each).
Step 3: Carefully press each puff pastry square into the cups of the prepared muffin tin, creating a small well for the filling.
Step 4: Place one cube of brie cheese into each pastry-lined cup. Top the brie with about 1 teaspoon of cranberry sauce, then sprinkle with a pinch of fresh chopped thyme.
Step 5: If using, brush the edges of the puff pastry with the beaten egg wash for a golden finish.
Step 6: Bake for 15-20 minutes, or until the puff pastry is golden brown and puffed, and the brie cheese is melted and bubbly. Watch carefully to prevent burning.
Step 7: Remove the muffin tin from the oven and let the bites cool for a few minutes before carefully transferring them to a serving platter. Garnish with additional fresh thyme and serve warm.