Apple Potato and Onion Gratin

Elevate your comfort food game with this Apple Potato and Onion Gratin—a rich and creamy casserole that brings together layers of tender russet potatoes, sweet-tart apples, and caramelized onions, all bathed in a luscious garlic-thyme cream and topped with a golden, bubbling blend of Gruyère and Parmesan cheeses. This stunning side dish strikes the perfect balance between savory and slightly sweet, making it a delightful pairing for holiday feasts or an impressive addition to your dinner table. With its velvety texture and elegant flavors, this gratin is a cozy yet sophisticated showstopper that’s sure to impress family and guests alike. Ready in just under two hours, its ease of preparation and restaurant-quality taste make it an essential addition to your recipe collection.

Nutriscore Rating: 62/100

Prep Time:20 mins

Cook Time:75 mins

Total Time:95 mins

Servings: 6

Ingredients

• 2 tablespoons Butter
• 2 large Yellow onion
• 2 teaspoons Salt
• 1 teaspoon Ground black pepper
• 2 large Apple (such as Granny Smith or Honeycrisp)
• 3 large Russet potatoes
• 1.5 cups Heavy cream
• 0.5 cups Whole milk
• 2 cloves Garlic
• 1 teaspoon Fresh thyme leaves
• 2 cups Gruyère or cheddar cheese (shredded)
• 0.5 cups Parmesan cheese (grated)

Directions

Step 1

Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with butter or nonstick cooking spray.

Step 2

Peel and finely slice the onions. In a large skillet, melt the butter over medium heat. Add the onions, 1 teaspoon of salt, and a pinch of black pepper. Cook, stirring occasionally, for 10-15 minutes until the onions become soft and golden brown. Remove from heat and set aside.

Step 3

Peel the apples, core them, and slice thinly (about 1/8 inch thick). Peel the potatoes and slice them thinly as well, preferably using a mandoline slicer for uniform thickness. Submerge the potato slices in cold water to prevent browning.

Step 4

Mince the garlic and set aside. In a medium saucepan, combine the heavy cream, milk, garlic, thyme leaves, 1 teaspoon of salt, and the remaining black pepper. Heat over medium-low heat until warm (do not boil). Remove from heat.

Step 5

Drain the potatoes and pat them dry with a clean kitchen towel.

Step 6

Layer one-third of the potato slices in the prepared baking dish, overlapping slightly. Top with half of the caramelized onions and half of the apple slices. Sprinkle 2/3 cup of Gruyère or cheddar cheese over this layer.

Step 7

Repeat with another third of the potatoes, the remaining onions, and the remaining apples. Sprinkle another 2/3 cup of Gruyère over the layer.

Step 8

Finish with the remaining potato slices. Pour the warm cream mixture evenly over the dish, ensuring it seeps through all the layers.

Step 9

Top with the remaining Gruyère and all of the Parmesan cheese.

Step 10

Cover the dish with aluminum foil and bake for 40 minutes. Remove the foil and bake for an additional 25-30 minutes, or until the top is golden brown and bubbly and the potatoes are tender when pierced with a knife.

Step 11

Remove from the oven and let rest for 10 minutes before serving. Garnish with additional thyme leaves, if desired.

Nutrition Facts

Serving size	2473.8 grams (2473.8g)

Amount per serving	% Daily Value*
Calories	4079

Total Fat 253.20g	325%
Saturated Fat 156.70g	783%
Polyunsaturated Fat 0.90g
Cholesterol 776mg	259%
Sodium 8424mg	366%
Total Carbohydrate 299.00g	109%
Dietary Fiber 31.20g	111%
Total Sugars 68.10g
Protein 136.40g	273%

Vitamin D 106IU	531%
Calcium 3309mg	255%
Iron 13mg	72%
Potassium 6432mg	137%

*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.

Source of Calories

Fat: 56.7%

Protein: 13.6%

Carbs: 29.7%