Gather the ingredients. Preheat an oven to 350 degrees F (175 degrees C). Butter a large baking dish.

Wash and peel potatoes so that only some of the peel remains on the potatoes; cut into 1/8 inch slices.

Arrange potatoes in the prepared dish.

Melt butter in a large pot over medium-high heat. Cook onion and garlic in melted butter until soft and translucent, 7 to 10 minutes; stir in broccoli soup, celery soup, milk, salt, pepper, and about 1/2 of the Cheddar cheese; cook until cheese has melted.

Pour cheese mixture over potatoes; top with remaining Cheddar cheese. Cover with aluminum foil or a lid.

Bake in the preheated oven for 45 minutes. Remove the cover and cook until the cheese begins to brown, about 10 minutes more.