Making a Scalloped Potato Gratin is so easy and so incredibly delicious that you’ll want to make it all the time. The flavor options are endless. One of my favorite gratin potato dishes is with roasted Poblano peppers. They give the dish a slightly smoky flavor.

Today, I’m making them with thinly sliced onions. Let me show you a few simple steps to making a Scalloped Potato Gratin.

Prep Time: 30 minutes (includes parboiling the potatoes)
Cook Time: 1 hour, uncovered
Total Time: 1 hour 30 minutes
Yields: 6 servings
Equipment: 1 (6-quart) saucepot, 2 (3-quart) saucepots, 1 (9 x 9) 2-quart baking dish, box grater, Mandolin, Microplane, chef’s knife, cutting board

Ingredients:
5 cups (2-pound bag) of baby Yukon gold potatoes, parboiled and sliced 1/8-inch thick
1 large sweet onion, thinly sliced
6 tablespoons of butter, unsalted, 3 tablespoons for greasing the baking dish
3 tablespoons of all-purpose flour
1 cup of whole milk, warm
1 cup of half-and-half, warm
1 1/2 tablespoons of kosher salt
1/2 teaspoon of black pepper, freshly-ground
1 teaspoon of smoked paprika
1/2 teaspoon of garlic powder
1/2 teaspoon of onion powder
1/4 teaspoon of cayenne pepper
1 pinch of nutmeg, freshly-grated
3/4 cup of Cabot white cheddar, freshly-grated
1/4 cup of Cabot Colby Jack cheese, freshly-grated, reserve 1/2 cup for topping
1/4 cup Parmesan cheese, freshly-grated for topping
2 tablespoons of fresh chives, minced
Garnish:
1/4 cup of Italian flat-leaf parsley, finely chopped

Instructions:
Preheat oven to 350°F.
First, generously butter the casserole dish.
Second, slice one large onion using a Mandolin and grate the cheese.
Third, parboil the Yukon gold potatoes until just fork-tender. The time may vary depending on the size of the potatoes.

Start by placing the potatoes into a large saucepot. Cover the potatoes with cold water. Over medium heat, bring the potatoes up to a boil. Once they are boiling, add 1 1/2 tablespoons of Kosher salt and continue cooking for 15 to 20 minutes. Take a paring knife and stick it into the center of one of the largest potatoes. If there is still some resistance to removing the knife, that’s fine, turn the heat off. Drain the potatoes and allow them to cool for about 10 minutes before slicing.

Once the potatoes have cooled enough to handle, use a Mandolin to slice them. Transfer the sliced potatoes to a large mixing bowl. Set aside.

In a small saucepan over medium heat, add half-and-half, whole milk, cayenne pepper, smoked paprika, onion powder, garlic powder, kosher salt, and fresh-ground black pepper. Bring the liquid to the *scalding point. Turn the heat off.

In another saucepan over medium-low heat, melt 3 tablespoons of unsalted butter. Once that’s melted, add the flour. Whisk the flour into the butter until paste-like and smooth. Add the warm milk mixture. Continue to whisk until the sauce thickens, about 5-7 minutes. Don’t rush the process; you’ll know when the sauce has reached the perfect thickness when it coats the back of a spoon.

Off the heat, I add some fresh chopped chives and freshly-grated cheese to the sauce. Here I’m adding a mixture of grated white cheddar and some yellow cheddar for color. I’m saving some back for the top. This way, the potato gratin will have a nice golden crust. I make sure to add the cheese slowly to the sauce, mixing it with a wooden spoon until the cheese has melted.

Add the minced chives. Stir to combine.

Place a layer of potatoes topped with half of the sliced onions. Pour half the milk sauce over the potatoes, then top with half the cheese mixture. Repeat a second layer the same way, finishing with the remaining sauce and grated cheese mixture. Sprinkle the top with freshly-grated Parmesan. Bake for 1 hour until bubbly and golden brown. Garnish with finely chopped Italian flat-leaf parsley. Allow the dish to rest for 10-15 minutes before slicing.

There you have it, my Scalloped Potato Gratin.

Notes:
1) *Scalded Milk is milk heated to a near boil. Small bubbles will start to appear around the rim of the pot.

2) The time may vary depending on the size of the potatoes.

3) Linda Lou Hamel is not a nutritionist or dietitian, and any nutritional information shared is an estimate. If calorie count and nutritional value are important to you, I recommend running the ingredients through a preferred online nutritional calculator of your choice. Calories and values can vary depending on the brands you choose.

https://lindalouhamel.com/2019/07/10/summer-time-flowers-and-herbs/