Start by heating your oven to 375°F so it's ready to go the moment your bread bowl is assembled. Using a serrated knife, cut a circle into the top of the boule, then pull out the bread inside with your fingers or a spoon. You want just enough room for the brie wheel to sit snugly in the center.
Cut small slits around the outer edge of the bread, spaced about an inch apart. This helps the crust toast evenly and makes it easier to tear off pieces later. Then take your paring knife and score the top of the brie in a crosshatch pattern so the jam can soak down into the cheese as it bakes.
Set the brie wheel into the hollowed-out center of the bread. Brush the melted butter generously over the top and sides of the loaf, making sure to get into those slits you cut earlier. This step is what gives the bread its golden, crackly finish.
Spoon the peach jam over the top of the brie, letting it pool into the scored cuts. Sprinkle the chopped candied pecans over everything, then finish with a light scattering of fresh thyme leaves if you're using them.
Slide the whole thing onto a baking sheet and into the oven for 20 to 30 minutes. You're looking for the brie to be completely melted and bubbly in the center, with the bread turning a deep golden brown around the edges.
Pull it out of the oven and let it sit for just a minute or two before serving; the center will be molten hot. Set it on your table with sliced apples and lemon cookies for dipping, and let everyone dig in while it's still warm.