Heat the oven to 450 degrees F. Cut 16 (1/2-inch thick) slices out of the loaf. Butter each side of the slices and put them onto a baking sheet. Spread 1 tablespoon of apple butter onto each slice. Top this with 1 slice of prosciutto and 3 or 4 slices of pear or apple. Cover this with the Brie slices, season with salt and pepper, and drizzle with olive oil. Bake until the cheese is melted, about 8 to 10 minutes.