Ultimate Hasselback Potato Casserole

The perfect hybrid of a creamy Gratin and crispy Hasselback potatoes.

Prep time: 25 minutes

Cook time: 1 hour 30 minutes

Total time: ~2 hours

Servings: 8–10

🛒 Ingredients

The Base

4–5 lbs Russet or Yukon Gold Potatoes: (About 8–10 medium). Russets provide the crispiest tops; Yukons provide a creamier interior.

2 cups Heavy Cream

4 cloves Garlic: Minced or grated.

1 tbsp Fresh Thyme Leaves: Roughly chopped (or 1 tsp dried).

2 tsp Kosher Salt

1 tsp Freshly Cracked Black Pepper

The Cheese & Toppings

1.5 cups Gruyère Cheese: Shredded (or Comté/Emmental for that nutty melt).

0.5 cup Parmigiano-Reggiano: Finely grated.

4 oz Bacon or Pancetta (Optional): Cooked until crispy and crumbled.

2 tbsp Unsalted Butter: For greasing the dish.

Garnish: Fresh chives or parsley.

🔪 Instructions

1. Prep the Oven and Dish

Preheat your oven to 400°F (200°C). Generously grease a 9x13-inch (or 3-quart) baking dish with the butter.

2. Prepare the Cream Mixture

In a very large mixing bowl, whisk together the heavy cream, minced garlic, thyme, salt, pepper, and half of the shredded Gruyère and Parmesan.

3. Slice the Potatoes

Using a mandoline slicer (highly recommended) or a very sharp knife, slice the potatoes into 1/8-inch thick rounds. Do not soak them in water; you want the starch to help thicken the sauce.

4. Toss and Coat

Add the potato slices to the large bowl with the cream mixture. Use your hands to toss them thoroughly, ensuring every single slice is separated and coated in the cream and cheese.

5. The Vertical Stack (The "Hasselback" Secret)

Pick up a handful of potato slices and organize them into a neat stack. Lay the stack in the baking dish with the edges aligned vertically (standing up on their sides).

Continue working around the perimeter and then the center until the dish is tightly packed.

Pour any remaining cream and cheese bits from the bowl evenly over the top.

6. The First Bake (Covered)

Cover the dish tightly with aluminum foil. Bake for 30 minutes. This steams the potatoes so the centers become tender.

7. The Second Bake (Uncovered)

Remove the foil. Bake for another 30–40 minutes. The cream will bubble and reduce, and the tops of the potatoes will start to turn pale golden.

8. The Final Crisp

Remove from the oven and sprinkle the remaining Gruyère, Parmesan, and the crispy bacon/pancetta over the top. Return to the oven for 15–20 minutes (or broil for 2–3 minutes) until the cheese is bubbling and the potato edges are deep golden brown and very crispy.

9. Rest and Serve

Let the casserole rest for 10 minutes before serving. This allows the sauce to set so it isn't runny when scooped. Garnish with fresh herbs.

💡 Expert Tips

Tight Packing: If you have extra potato slices, wedge them in! The tighter they are packed, the better they stand up and the more "fans" you get.

Mandoline Safety: Always use the guard when slicing potatoes. It ensures perfectly even slices which is the key to even cooking.

Make-Ahead: You can assemble the dish through Step 5 up to 24 hours in advance. Keep it covered in the fridge, then bake as directed (adding 10 minutes to the covered bake time).