Combine potatoes, eggs, and milk together in a large bowl.

Stir flour, Parmesan cheese, Cheddar cheese, bacon bits, onion salt, baking powder, salt, and black pepper into potato mixture using a fork.

Heat corn oil and butter in a large skillet over medium heat.

Drop potato mixture by 2 tablespoonfuls onto skillet. Cook patties until golden brown, about 4 minutes per side

Drain cooked pancakes on a paper towel-lined plate.