Set your oven to 350°F and let it fully heat up before your brie goes in. Line a baking sheet with parchment paper so nothing sticks and cleanup stays easy. I always do this first so the oven is ready the moment my brie is wrapped.
Unroll your crescent dough sheet on a flat surface and cut it into two even rectangles. Place one rectangle in the center of your prepared baking sheet. This bottom piece is what will cradle your brie wheel, so make sure it's centered.
Place your wheel of brie right in the middle of the bottom dough rectangle. I like to give it a gentle press so it sits flat and centered, which makes wrapping easier in the next step.
Lay the second dough rectangle over the top of the brie. Press down gently around the edges of the cheese so the two pieces of dough start to meet and seal around it.
Fold the bottom dough up and around the sides of the brie, pressing the seams together with your fingers. I make sure every gap is pinched shut here, since any opening lets the cheese leak out while baking.
Using your pastry brush, coat the entire outside of the wrapped brie with the beaten egg. This step is what gives the crust that deep golden color and glossy shine once it's baked.
Slide the tray into the oven and bake for 20-25 minutes, until the pastry turns a rich golden brown all over. Let it rest for 10-15 minutes once it's out, since the cheese inside is extremely hot.
Transfer your baked brie to a serving platter using a spatula so the bottom doesn't tear. Serve it warm alongside crackers, sliced fruit, or crusty bread while the center is still soft and pourable.