3-cheese scallopped potatoes

1 ½ lbs potatoes, scrubbed, thinly sliced
1 small onion, finely diced
2 tbs flour
salt, pepper to taste
¼ cup parmesan cheese, finely grated
1 cup grated aged cheddar cheese
¼ cup crumbled blue cheese
1 cup whole milk

In a large bowl, using your hands to coat evenly, toss together potatoes and onion with flour, salt, pepper and parmesan cheese. Arrange half in a baking dish and sprinkle with half of each of the cheddar and blue cheese. Arrange remaining potatoes on top.

Bring milk to a simmer over med-high heat. Pour milk over potatoes. Cover baking dish and bake at 400 degrees for 35 minutes. Uncover and top with remaining cheese. Bake for another 20 minutes, until potatoes are cooked through and cheese is bubbly and browned. Remove from oven and let set for 5 minutes before serving.