Start with 12 crostini, either homemade from a French baguette or store-bought. I like making them ahead because it saves time on the day. Toasted bread holds up better under the melted cheese.
Cut the brie into slices about 1/4 inch thick. Thin slices melt evenly and don't overpower the apple. I keep the rind on, since it softens nicely in the oven.
Place the crostini in a single layer on a rimmed baking sheet. Set one slice of brie on top of each piece. Leave a little space between them so the heat circulates.
Heat your oven to 350°F. Slide the baking sheet in and bake for 5 minutes. You want the cheese soft and melted, not runny or browned.
While the crostini bake, cut your apple into thin slices. I cut them thin enough to lay flat on the bread. Slice just before serving so the apple stays fresh and bright.
Pull the crostini from the oven and layer an apple slice on each. Drizzle honey over the top. Finish with fresh cracked pepper and a few thyme leaves.
Move the crostini to a platter while they are still warm. The cheese is at its best in the first few minutes. I always set them out right away so nobody misses that gooey bite.