Preheat your oven to 200°C (390°F) and line a baking sheet with parchment paper.
Unfold the puff pastry sheet on a lightly floured surface and gently roll it out just to even the surface. Use a knife or pastry cutter to cut the pastry into 24 small squares, about 2 inches each.
Arrange the pastry squares evenly spaced on the prepared baking sheet, leaving room for expansion.
Bake the pastry squares in the preheated oven for 8-10 minutes, until they just start to turn golden around the edges and are crisp to the touch.
While the pastry bakes, rinse the cranberries and pat them dry. If using fresh cranberries, you can toss them with a teaspoon of sugar and some lemon zest for extra flavor, but this step is optional.
Remove the pastry from the oven and let it cool for about 2 minutes on a cooling rack. This helps prevent the cheese from melting too quickly and sticking.
Top each pastry square with a small slice of Brie cheese, pressing lightly to help it settle.
Place a few cranberries on top of each Brie-topped pastry, distributing them evenly for a colorful and tart contrast.
Return the baking sheet to the oven and bake for an additional 5-7 minutes, until the Brie cheese has melted and the cranberries are softened and slightly bursting.
Remove from the oven, and if desired, drizzle with honey and sprinkle with fresh thyme for added flavor. Let the bites sit for 2 minutes to settle.
Serve the cranberry Brie bites warm or at room temperature, enjoying their crisp, gooey, and tart harmony in every bite.