This Cheesy Rosemary Mashed Potato Casserole may be the best mash you’ll ever eat. It has everything you want from your favorite side dish, creamy, cheesy, full of rosemary flavor with a crispy topping.

This is recipe #3 in this weeks complete holiday dinner series. In case you missed them, I’ve already published slow cooker green beans with shallots and almonds and the star of the table, herb roasted beef tenderloin.

I don’t really know where to start talking about this casserole. I do know I ate too much of it before I sat down for my meal and I do know that any holiday dinner, whether it’s Thanksgiving or Christmas, really good mash is mandatory.

Mash until your arm hurts for no lumps

The key to really soft and creamy mash is first, you have to mash really well. If there are any lumps, well, no mash really should have lumps. I live by my ricer for mashed potatoes. if you haven’t seen a ricer, it’s like a giant garlic press. You can see it in the video below.

Cheesy rosemary mashed potato casserole in a white casserole dish fresh out of the oven with green beans

A great make ahead dish

This is the perfect dish to take some help from prepping ahead. You can make this a couple of days before your holiday dinner. Make up to the point of baking but don’t add the panko and Parmesan. Cover and refrigerate until ready to bake, add the toppings then as directed in the recipe. How easy was that?

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Cheesy Rosemary Mashed Potato Casserole

Name: Cheesy Rosemary Mashed Potato Casserole
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Yield: 8
Cuisine: American
Ingredients: 5 pounds Yukon gold potatoes, peeled and quartered; 2 tablespoons salt; 2 cups heavy cream, warm; 1/2 cup unsalted butter, melted; 8 ounces white cheddar cheese, grated; 8 ounces mozzarella cheese, grated; 2 tablespoons fresh rosemary, chopped; 1/2 teaspoon ground black pepper; 1 cup panko breadcrumbs; 1 cup Parmesan cheese, grated

Yield: 8

Prep Time: 10 minutes

Cook Time: 45 minutes

Total Time: 55 minutes

This cheesy rosemary mashed potato casserole may be the best mash you'll ever eat. It has everything you want from our favorite side dish. Creamy, cheesy, full of rosemary flavor with a crispy topping.

Ingredients

5 pounds Yukon gold potatoes, peeled and quartered
2 tablespoons salt
2 cups heavy cream, warm
1/2 cup unsalted butter, melted
8 ounces white cheddar cheese, grated
8 ounces mozzarella cheese, grated
2 tablespoons fresh rosemary, chopped
1/2 teaspoon ground black pepper
1 cup panko breadcrumbs
1 cup Parmesan cheese, grated

Instructions

Add the potatoes to a large pan and cover with water. Bring to a boil, add the 2 tablespoons salt and simmer for 15 minutes until tender. Drain and add to a large bowl.
Preheat oven to 375°F. Butter the inside of a 9 x 13-inc casserole dish.
Run the potatoes through a ricer or food mill or mash really well to get the smoothest mash possible
Add the cream, butter, cheeses, rosemary and pepper. Stir until combined and the cheese is melted. Taste and add salt if needed (I did not since I added it to the boiling water as well as the cheese are salty).
Pour the mash into the casserole dish and spread evenly. Mix the breadcrumbs and Parmesan in a bowl. Sprinkle an even layer of breadcrumbs and Parmesan cheese on top of the mashed potato.
Bake for 30 minutes until the top is golden.