Go Back

Tuna Scalloped Potato Casserole

Course Main Course
Cuisine American
Prep Time 15 minutes
Cook Time 1 hour 10 minutes
Servings 8


  • 2 pounds potatoes
  • 1 medium onion
  • 4 cloves garlic
  • ¼ bunch fresh chives
  • ¼ cup ground oats
  • 1 cup shredded sharp cheddar
  • 3 tablespoons olive oil
  • 2 tablespoons all purpose flour
  • 3 cups milk
  • 3 cans tuna fish drained
  • 1 cup frozen or fresh peas
  • salt and black pepper


  1. Preheat oven to 375F.
  2. Scrub the outside of the potatoes well. Thinly slice the potatoes with a mandoline or with a chef’s knife, cutting out any dark spots. Put the sliced potatoes in a bowl with water to soak.
  3. Peel and dice the onion and mince the garlic. Chop the chives.
  4. Pour the ground oats, shredded cheddar, and half of the chives into a bowl and mix well.
  5. Drain the sliced potatoes in a colander of any excess water and allow them to drain completely while preparing the sauce.
  6. Heat the olive oil in a large skillet over medium-high heat. Add the onion and garlic to the pan and saute 3-4 minutes. Sprinkle the flour over the pan and stir well for it to soak up the oil and become like a thick paste. Let it cook 2-3 minutes, stirring continuously, before adding in the milk. Stir well and allow it to simmer for it to thicken; about 6 minutes.
  7. Stir the tuna fish into the sauce. Add the peas and the rest of the chives to the sauce and stir again. Taste and season with salt and pepper as needed. Turn off the heat.
  8. Ladle some of the sauce into the bottom of a casserole dish before adding a layer of sliced potatoes on top. Add more sauce to the potatoes and then layer potatoes again. Repeat this process until all the potatoes and sauce are added finishing with sauce on top. Sprinkle the ground oats and cheese mixture on top of the casserole and cover with aluminum foil.
  9. Bake the tuna scalloped potato casserole for 35 minutes. Remove the aluminum foil and let it cook another 10 minutes for the top to brown. Remove the casserole from the oven and allow to cool for 10 minutes before serving.