Unroll piecrust, and fit into a 9 1/2" deep-dish pie plate according to package directions. Fold edges under, and crimp. Spoon dollops of dulce de leche into piecrust, spreading to edges. Place prepared piecrust in refrigerator.
Whisk eggs in a medium bowl. Whisk in pumpkin and next 7 ingredients until smooth. Whisk in milk. Pour filling into prepared piecrust. Bake at 375° on bottom oven rack for 48 to 50 minutes or until pie is just set (center will still jiggle just slightly). Cool completely on a wire rack. Garnish, if desired.