Step 1

Preheat oven to 350 degrees F (175 degrees C).

Step 2

Stir mashed sweet potatoes, white sugar, 1/2 cup butter, milk, eggs, cinnamon, and vanilla together in a large bowl until smooth; transfer to a casserole dish.

Step 3

Mix brown sugar, pecans, coconut, and 1/2 cup butter in a bowl; spread atop the filling.

Step 4

Bake casserole in preheated oven until topping is golden brown, about 30 minutes.