two-potato gratin

Recipe by
Lynette !
Gulf Breeze, FL

I love gratin potatoes....this one is a bit of an effort. I think nothing of making the sauce....my grandma was always making these sauces in an attempt to get us to eat veggies. LOL. The combination of sweet and baking potatoes adds a depth of flavor.

yield 8 serving(s)
prep time 30 Min
cook time 1 Hr 10 Min
method Bake

Ingredients For two-potato gratin

  • 2 md
    baking potatoes, peeled and cut into 1/4 inch thick slices (about 3 cups)
  • 2 md
    sweet potatoes, peeled and cut into 1/4 inch thick slices (about 4 cups)
  • 2 qt
    low sodium chicken stock
  • 2 Tbsp
    canola oil
  • 3 Tbsp
    all-purpose flour
  • 2 clove
    garlic, crushed
  • 1 1/2 c
    milk
  • 2 sprig
    thyme
  • 3/4 tsp
    kosher salt, divided
  • 1/4 tsp
    black pepper, freshly ground
  • 3 oz
    gruyere cheese, shredded (about 3/4 cup)
  • cooking spray
  • 2 Tbsp
    fresh chives, chopped, divided
  • 1 1/2 tsp
    fresh thyme, chopped
  • 1 oz
    fresh parmigiano-reggiano cheese, grated (about 1/4 cup)

How To Make two-potato gratin

  • 1
    Preheat oven to 350 degrees.
  • 2
    Place potatoes in a large stockpot; cover with stock. Bring the mixture to a boil. Cook 4 minutes. Remove from heat. Carefully remove the potatoes from the pot using a slotted spoon, reserving the cooking liquid. Arrange the potato slices in a single layer on a jelly-roll pan; set aside.
  • 3
    Strain the cooking liquid through a fine mesh sieve over a bowl; reserve 1 cup cooking liquid. Discard the solids and the remaining cooking liquid.
  • 4
    Heat a medium saucepan over medium heat. Add the oil to the pan. Sprinkle the flour over the oil; cook 1 minute, stirring constantly with a whisk. Add the garlic; cook 2 minutes, stirring frequently. Combine milk and reserved 1 cup cooking liquid. Gradually pour milk mixture into the flour mixture in pan, stirring constantly with a whisk. Add thyme sprigs to the pan. Bring mixture to a boil; cook 4 minutes or until slightly thick, stirring frequently. Remove from the heat. Strain mixture through a fine-mesh sieve over a bowl, reserving sauce; discard solids. Stir 1/2 teaspoon salt, pepper, and Gruyere cheese into the sauce.
  • 5
    Spread 1/2 cup sauce in the bottom of a broiler-safe 2 quart ceramic baking dish coated with cooking spray. Arrange a single, flat layer of sweet potato and then baking potato slices over the sauce. Over the flat layer, alternate baking potato and sweet potato slices, in shingle-like fashion. Sprinkle evenly with remaining 1/4 teaspoon salt, 1 tablespoon chives, and shopped thyme; pour remaining sauce over the potato mixture. Sprinkle with Parmigiano-Reggiano cheese. Bake at 350 degrees for 1 hour or until the potatoes are tender when pierced with a knife.
  • 6
    Remove gratin from the oven. Preheat the broiler to high.
  • 7
    Place the gratin in the oven. Broil the gratin 3 minutes or until lightly browned. Sprinkle with the remaining 1 tablespoon chives.
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