It only takes six ingredients to bake up a batch of these sumptuous, elegant appetizers—which means those ingredients have nowhere to hide, so buy the best you can. When you do, this dish will sing with a mixture of salty, sweet, and tangy flavors.
Preheat oven to 400°F. Cover phyllo dough with a dampened cloth to keep it from drying out as you work.
Place 1 sheet of dough on a work surface and lightly brush with some melted butter. Layer another sheet on top and brush the surface with more butter. Repeat until you have 6 sheets layered. Repeat process to make another 2 stacks with 6 layers of phyllo each.
Use a 3-inch cookie cutter to cut out 24 rounds from the 3 stacks of layered phyllo. Press each round one into a well of a mini muffin pan. Fill with dried beans or pie weights and bake for 8-10 minutes, or until lightly golden brown.
Remove from the oven and let cool 5 minutes, then remove the pie weights and transfer to a parchment-lined baking sheet. Reduce oven temperature to 350°F.
Cut brie into 24 ½-inch cubes. Place each cube in a phyllo cup and top with a teaspoon of raspberry preserves and ½ teaspoon of walnuts. Bake for 10-12 minutes, or until just melted.