Combine pecans, brown sugar, syrup,vanilla, and egg white, stirring well.
Spoon about 1 teaspoon sweet potato mixture into each phyllo shell, spreading to edges. Spoon about 1/2 tspn of pecan mixture over sweet potato mixture. Place filled shells on an ungreased baking sheet. Bake at 350F for 20 minutes. Cool completely on a wire rack. Serving size: 2 tarts.