Baked Mashed Potatoes with Parmesan

INGREDIENTS

lbs yellow potatoes or russet potatoes, (peeled and cut into 1 1/2-inch pieces)

1/2 cup

unsalted butter, (cut into 4 pieces)

garlic cloves, (minced (2 tsp))

1 cup

whole milk, (then more as desired)

1 cup

freshly grated parmesan cheese

1 1/2 cups

freshly grated mozzarella cheese

Salt

2 1/2 tbsp

chopped fresh parsley ((optional))