Potato Gratin Recipe

Introduction

Potato gratin is a rich and comforting dish that transforms simple sliced potatoes into a creamy, cheesy delight. This version uses sweet potatoes for a slightly sweet and savory flavor, layered with a fragrant herb and cheese sauce that bakes to golden perfection.

Ingredients

• 3 lbs sweet potatoes, peeled, rinsed, and thinly sliced into 1/8” rounds (mandoline slicer preferred)
• 4 tbsp butter
• 2 cloves garlic, minced or pressed
• 1 small red onion, finely diced
• 1 tbsp all-purpose flour
• 1 cup heavy cream
• 1 cup half and half or whole milk
• 1/2 tbsp finely chopped fresh rosemary leaves
• 1 tsp smoked paprika
• 1/4 tsp ground sage
• 1/2 tsp Diamond Kosher salt
• 1/4 tsp freshly ground black pepper
• 1/4 tsp freshly grated nutmeg
• 1/3 cup grated asiago cheese
• 1 cup smoked gouda cheese, shredded (divided)
• 1 cup Colby Jack cheese, shredded (divided)

Instructions

1. Step 1: Preheat your oven to 400 degrees Fahrenheit. Melt butter in a large saucepan over medium heat.
2. Step 2: Add garlic and diced onions to the melted butter. Cook, stirring occasionally, until softened, about 5 minutes.
3. Step 3: Stir in the flour and cook for 1 minute, stirring occasionally to combine well.
4. Step 4: Slowly whisk in the heavy cream and half and half. Increase heat to medium-high and cook for 3-4 minutes, stirring occasionally, until the sauce thickens and begins to bubble. Immediately remove from heat.
5. Step 5: Stir the asiago cheese, fresh rosemary, smoked paprika, sage, salt, pepper, and nutmeg into the sauce. Let it cool to room temperature.
6. Step 6: While the sauce cools, peel and slice the sweet potatoes very thin (about 1/8 inch) using a mandoline or sharp knife.
7. Step 7: Grease a baking dish with butter or cooking spray. Arrange the potato slices in a circular pattern in the dish. If you prefer, you can toss the slices flat with the sauce before layering.
8. Step 8: Once the sauce is cool, stir in half of the Colby Jack and half of the smoked gouda cheese. Pour the sauce evenly over the potatoes in the dish.
9. Step 9: Sprinkle the remaining Colby Jack and smoked gouda cheeses on top.
10. Step 10: Cover the dish tightly with foil and bake for 45-50 minutes, until potatoes are tender and easily pierced with a knife.
11. Step 11: Remove the foil and bake uncovered for an additional 15-20 minutes, or until the top is golden brown. Let rest for 10-15 minutes before serving.

Tips & Variations

• Use a mandoline slicer for even, thin potato slices that cook uniformly.
• For extra browning, bake a few minutes longer uncovered or briefly broil—watch carefully to avoid burning.
• Swap sweet potatoes for Yukon Gold or Russet potatoes if you prefer a classic gratin flavor.
• Add a pinch of cayenne pepper for a subtle spicy kick.

Storage

Store leftover gratin covered in the refrigerator for up to 3 days. Reheat in a 350-degree oven until warmed through, about 15-20 minutes. Avoid microwaving to preserve the creamy texture and avoid sogginess.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I prepare this gratin ahead of time?

Yes, you can assemble the gratin a day ahead and refrigerate it covered. Bake it when ready, adding a few extra minutes to the cooking time if starting cold.

Can I use a different cheese instead of Asiago or Gouda?

Absolutely! Gruyère, Parmesan, or sharp cheddar make great substitutes and will alter the flavor profile slightly but deliciously.

Potato Gratin Recipe

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★★★★★

4.9 from 72 reviews

A creamy and flavorful Potato Gratin made with thinly sliced sweet potatoes baked in a rich, cheesy sauce infused with garlic, fresh herbs, and warm spices. This comforting dish layers smoked gouda, Colby Jack, and asiago cheeses with a creamy herb sauce, perfect as a hearty side or vegetarian main.

• Author: lea
• Prep Time: 20 minutes
• Cook Time: 65 minutes
• Total Time: 1 hour 25 minutes
• Yield: 8 servings 1x
• Category: Side Dish
• Method: Baking
• Cuisine: American
• Diet: Vegetarian

Ingredients

Scale 1x2x3x

Potatoes

• 3 lbs sweet potatoes, peeled, rinsed, and thinly sliced into 1/8” rounds (mandoline slicer preferred)

Sauce

• 4 tbsp butter
• 2 cloves garlic, minced or pressed
• 1 small red onion, finely diced
• 1 tbsp all-purpose flour
• 1 cup heavy cream
• 1 cup half and half or whole milk
• 1/2 tbsp finely chopped fresh rosemary leaves
• 1 tsp smoked paprika
• 1/4 tsp ground sage
• 1/2 tsp Diamond Kosher salt
• 1/4 tsp freshly ground black pepper
• 1/4 tsp freshly grated nutmeg

Cheese

• 1/3 cup grated asiago cheese
• 1 cup smoked gouda cheese, shredded (divided)
• 1 cup Colby Jack cheese, shredded (divided)

Instructions

1. Preheat Oven: Preheat your oven to 400°F (204°C) to prepare for baking the gratin.
2. Cook Aromatics: Melt butter in a large saucepan over medium heat. Add minced garlic and diced red onion, cooking and stirring occasionally until softened, about 5 minutes.
3. Make Roux: Stir in the all-purpose flour and cook for 1 minute, stirring occasionally to avoid lumps.
4. Add Dairy: Slowly whisk in the heavy cream and half and half (or whole milk) until well combined.
5. Thicken Sauce: Increase heat to medium-high and cook for 3-4 minutes, stirring occasionally, until the sauce slightly thickens and begins to bubble. Remove from heat immediately.
6. Season Sauce: Stir in grated asiago cheese, chopped fresh rosemary, smoked paprika, ground sage, kosher salt, black pepper, and freshly grated nutmeg. Let the sauce cool to room temperature to prevent cheeses from melting prematurely.
7. Prepare Potatoes: While sauce cools, peel and thinly slice sweet potatoes using a mandoline or sharp knife (aim for 1/8” thickness).
8. Arrange Potatoes: Grease a baking dish with butter or cooking spray. Arrange potato slices in a circular overlapping pattern. If not layering, toss potato slices with sauce and proceed to the next step.
9. Combine Cheese and Sauce: Once cooled, stir half of the Colby Jack and half of the smoked gouda cheeses into the sauce. Note that the cheese will not melt at this stage.
10. Assemble Dish: Pour the sauce evenly over arranged potatoes in the casserole dish. Top with the remaining shredded Colby Jack and smoked gouda cheeses.
11. Bake Covered: Cover the dish tightly with foil and bake in the preheated oven for 45 to 50 minutes, or until potatoes are tender and can be easily pierced with a knife.
12. Bake Uncovered: Remove the foil and continue baking for another 15 to 20 minutes until the top turns golden brown and bubbly.
13. Rest and Serve: Let the gratin rest for 10 to 15 minutes before serving warm. For extra browning, optionally broil briefly while watching carefully to avoid burning, if your dish is broiler-safe.

Notes

• Use a mandoline slicer to ensure evenly thin potato slices for uniform cooking.
• If layering potatoes flat instead of circularly, mix them thoroughly with the sauce before placing in the baking dish.
• Allowing the sauce to cool before combining with cheese prevents premature melting and ensures even distribution.
• Substitute half and half with whole milk for a lighter sauce if desired.
• For a crisper top, broil briefly at the end but watch closely to prevent burning.
• This dish can be prepared ahead and baked just before serving.
• Leftovers refrigerate well and can be reheated gently in the oven.

Keywords: Potato Gratin, Sweet Potato Gratin, Cheesy Potato Casserole, Holiday Side Dish, Creamy Potatoes, Baked Sweet Potatoes, Vegetarian Potato Dish