Prepare the phyllo layers:
Lay out one sheet of phyllo dough and brush it lightly with melted butter. Layer another sheet on top and brush with more butter. Repeat until you have a stack of 6 sheets.
Cut the stack into rectangles (about 4×4 inches) and place them on the prepared baking sheet. Repeat with the remaining phyllo sheets to create more layers.
Bake the phyllo:
Bake the phyllo rectangles for 8-10 minutes, or until golden brown and crispy. Let them cool slightly.
Assemble the pastry:
Place one baked phyllo rectangle on a serving plate and layer it with sliced Brie, a spoonful of cranberry sauce, and a sprinkle of chopped pecans.
Add another phyllo rectangle on top and repeat the layering process with more Brie, cranberry sauce, and pecans. Finish with a final layer of phyllo on top.
