Skillet Scalloped Potato Gratin is a decadent side dish that combines the richness of scalloped potatoes and the cheesiness of au gratin.

Looking for more cast iron potato recipes? Try our Skillet Fondant Potatoes, Dutch Oven Baked Potatoes, or Cheesy Hasselback Potatoes.

Freshly baked and rested Skillet Scalloped Potato Gratin garnished with fresh thyme sprigs, and potatoes and a serving spoon off to the sides.

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What’s the difference between scalloped and au gratin potatoes?
Methods for slicing potatoes thinly
How to make Skillet Scalloped Potatoes Gratin
Other Related Cast Iron Side Dish Recipes
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Oh my delicious.

These Skillet Scalloped Potato Gratin are fancy, decadent, and rich to be worthy of your holiday or entertaining table.

Yet, they're right at home plated with your favorite Monday meatloaf.

What’s the difference between scalloped and au gratin potatoes?

Without going into a exhaustive explanation of the culinary history of both dishes, there's a simple and generally accepted definition for the two potato dishes.

Scalloped potatoes are thinly sliced (but thicker than our recipe here) into rounds and baked in a cream sauce sans cheese.

A serving of Skillet Scalloped Potato Gratin on a white plate with a fork. The red skillet in the background and fresh thyme garnishing the potatoes and in the background.

Au gratin potatoes are thinly sliced layered in a baking dish/pan with grated cheese between the layers.

Our recipe truly combines the best of both potato recipes.

Methods for slicing potatoes thinly

There’s a few ways you could slice your potatoes thinly for this and others recipes like it.

by hand, with a sharp chef’s knife
with a food processor using the slice blade
using a mandolin slicer
and believe it or not, I’ve even used my apple corer peeler slicer gizmo

Half of a russet potato resting on a mandolin slicer, showing a slice of potato from both the thinner and thicker side of the blade.

How to prevent sliced potatoes from turning brown

I prefer to get all of my potatoes sliced and ready to go before I move on with any other prep work or assembling the recipe.

For this recipe, I used my mandolin slicer on the thicker of the blade settings. I filled a large bowl with water and a lot of salt. As you go, place the sliced potatoes in the salted water.

The salty water will prevent the potatoes from turning brown. I simply drain and rinse them before layering the casserole. Make sure to shake off any excess water.

Sliced potatoes soaking in a bowl of salted water.

How to make Skillet Scalloped Potatoes Gratin

First off, this isn’t a difficult recipe to make. But it most certainly is one you want to have all your prep done and a game plan for how you’re going to make it.

You can slice your potatoes first or you can slice them last. You can make the sauce first or you can make the sauce last.

This isn’t one of those recipes that you begin having only read the first step.

Ingredients to make Skillet Scalloped Potato Gratin.

All right, I’m assuming you have sliced, diced, grated, measured, and are ready to go.

If not, stop, get it done, then come back. I'll wait. (Yes, I can be boss daddy too!)

Prepping to make Scalloped Potato Gratin

Preheat your oven to 325°F.

Coat the inside of your skillet with softened butter.

Grate the onion. However, if you don't want to grate it, dice it finely.

Image showing both grated onion and finely diced onion, with the grater and knife in the background.

In a medium sauce pan, whisk the cream, garlic, onion, thyme, pepper, and nutmeg together. Bring it to a soft boil over medium heat. You don’t want a raging boil for fear of scalding the cream. Have you ever tasted burnt cream? Nasty.

Reduce the heat to low and allow it to simmer for about 15 minutes. It will start to thicken and come together.

Just give it a good stir or whisking occasionally, cream really does like to scald or stick to the bottom of the pan.

Ingredients to make cream sauce in a sauce pan.

Drain and rinse (with cold water) the potatoes. Give them a hardy shake while in the sieve. While the potatoes drained for a quick-tick in the sink, I wiped out the bowl to use again.

Toss the potatoes back in the bowl, de-clumping any major potato clusters, pour the cream over the potatoes. Mix it all really well.

Skillet Scalloped Potato Gratin presentation

Now, if you’re not worried about appearance, you can dump that entire mixture into your skillet and smooth it out. And let's face it, sometimes we just don't care about it being pretty.

Sliced potatoes with the cream sauce mixed in.

But if you wanting an elegant presentation, then you’ll need to layer the potatoes by hand, individually.

To do this, simply grab a handful of potatoes, hold over the bowl to allow the excess cream to drip off, and layer evenly along the bottom of the skillet.

Repeat this process, layer by layer, until you have used all the potatoes and only the cream sauce remains in the bowl.

Once layered, you'll have a little pool of sauce in the pan.

Pour the remaining cream sauce over the potatoes. Use a spoon to smooth it out. Make sure it fills in all the nooks and crannies and along the side.

Remaining cream sauce has been poured over the layered potatoes.

Sprinkle the cheddar over the top and garnish with a few fresh thyme leaves.

You can omit the thyme if you want. I think it makes the dish look a bit prettier and gives it a pop of color. It's rather dull looking without it.

Cover tightly with foil or the skillet lid, if it has one. Bake for 60 minutes covered.

Remove the foil or lid and allow to bake for another 15 minutes uncovered. The cheese will melt and brown.

Once done, remove from the oven and lightly cover with the foil or lid (placed askew).

Don't cover tightly. It will sweat and condensation will form. No one likes soggy or watery potatoes. (I'm sure someone does and they'll eventually tell me that in the comments.)

Allow the potatoes to rest for 5-10 minutes.

If you serve them immediately, it could fall apart. You'd have one tasty hot mess on your hands. Resting before serving will help solidify the potatoes giving the sauce and cheese time to settle.