Step 1

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

Step 2

Layer half the potatoes, half the ham, and half the onion in an 2-quart baking dish; repeat the layers.

Step 3

Heat milk, peas, flour, butter, salt, black pepper, garlic powder, and onion powder in a saucepan over medium heat, stirring constantly, until thickened, 7 to 10 minutes.

Step 4

Stir Cheddar cheese into sauce until cheese is melted.

Step 5

Pour sauce over potato and ham mixture; sprinkle with paprika.

Step 6

Cover baking dish with aluminum foil.

Step 7

Bake in the preheated oven until potatoes are tender, about 1 hour.

Step 8

Remove foil and continue baking until lightly browned, about 15 minutes more.