Creamy Mashed Potato Casserole
Gluten Free,  Salads & Side Dishes,  Vegetarian

Easy Creamy Mashed Potato Casserole

Creamy Mashed Potato Casserole gets a little flavor love with the addition of sour cream and cream cheese.

This recipe is the perfect make-ahead side dish that can be reheated in the oven or the microwave.

These creamy potatoes are fluffy with a nice buttery flavor.

Perfect if you ask me!

Creamy Mashed Potato Casserole
Sliced Twice Baked Potatoes

The Potatoes

For this recipe you’ll need 5 pounds of russet potatoes, or about 6 bakers. I find this variety of potato to yield the perfect smooth and creamy consistency.

No gritty or gluey mashed potatoes here. Please tell me you know what I’m referring to :)

Creamy Mashed Potato Casserole

The Cooking Method

Peel and cut potatoes into about 6-8 pieces each and place in large pot of salted cold water. Add a bay leaf, a few sprigs of fresh thyme, a couple garlic cloves and salt to the water. Thank you to the Kitchn for this recipe tip!

We’re going to take advantage of any opportunity to infuse flavor into our potatoes. If you don’t want flecks of thyme leaves in your potatoes you can place the fresh herbs in a cheese cloth bundle, then discard after boiling.

Creamy Mashed Potato Casserole

Cook potatoes just until *fork tender, then drain and return to the hot cooking pot to dry. Remove and discard the thyme and bay leaf before mashing.

*the ideal way to achieve fork tender potatoes is when you can insert a fork easily but still lift the potato from the water before it falls off. Not scientific, but tried and true.

I still use a good old fashioned potato masher but have heard of great results when using a potato ricer as well. For best results, please resist the urge to use an electric mixer which tends to deliver a gluey mash.

Add the following ingredients to the mashed potatoes:

  • butter (1/2 cup)
  • cream cheese (8 ounces)
  • 1 cup sour cream
  • 1 cup whole milk
  • salt & pepper to taste

Continue to mash until well combined. Transfer potatoes to a 9×13 baking dish. Add dollops of butter to top, cover and refrigerate until ready to bake.

The beauty of this recipe is it can be made up to 2 days in advance of serving. And you can reheat in the oven or microwave.

Oven Heating Method

Oven heating is my preferred method because we love the buttery golden top.

  • Preheat oven to 350 degrees F.
  • Remove potatoes from refrigerator and allow to rest at room temperature
  • Bake uncovered for about 45 minutes or lightly browned and heated through
  • Heating times will vary depending on oven and if multiple dishes are being heated together
  • Tent with foil If casserole begins to brown too quickly

Microwave Heating Method

Reheating in the microwave comes in very handy, especially during the holidays when oven space is in high demand.

  • Microwave potatoes uncovered on high in one minute increments
  • Stir after each minute, until hot

Family Favorite Side Dishes

If you’re planning your Thanksgiving or Holiday menu, here are a few our our family’s favorite side dishes.

Creamy Mashed Potato Casserole

Everyone loves mashed potatoes. When you’re planning a big meal, go ahead and make this side dish in advance. One less thing to worry about as you’re enjoying the company of friends and family.

Don’t forget to follow us @LemonyThyme on Instagram and Facebook! And check out our latest TikTok videos and Pinterest boards too!

All my best,
xo Libby

Creamy Mashed Potato Casserole

Creamy Mashed Potato Casserole gets a little flavor love with the addition of sour cream and cream cheese.
5 from 2 votes
Prep Time 10 minutes
Cook Time 20 minutes
Reheating Time 45 minutes
Course Side Dish
Servings 12


  • 5 pounds russet potatoes, about 6 bakers peeled and cut into 6-8 pieces each
  • 4 sprigs fresh thyme
  • 4 garlic cloves peeled
  • 1 bay leaf
  • 1 Tablespoon kosher salt
  • 1 stick butter (1/2) cup, plus 2 Tbl. for top of casserole room temperature
  • 8 ounces cream cheese room temperature
  • 1 cup sour cream
  • 1 cup whole milk
  • salt & pepper to taste


  • Place peeled & cut potatoes into a large pot of cold water. Add thyme, garlic, bay leaf and salt. Bring to a boil over high heat, then reduce heat to medium-high and continue cooking until just *fork tender.
    *fork tender is when you can insert a fork easily into a potato and lift it slightly out of the water before it falls off fork.
  • Once potatoes are fork tender, drain and return to cooking pot to continue to dry. Using a potato masher or potato ricer mash potatoes.
  • Add butter, cream cheese, sour cream and milk and continue to mash until smooth and creamy. Season with salt & pepper to taste. Transfer potatoes to a 9×13 casserole dish. Cover and refrigerate for up to 2 days.

Oven Reheating Method

  • Remove casserole from refrigerator and allow to rest while oven is preheating. Preheat oven to 350° F. Bake casserole uncovered for about 45 minutes, until top is lightly golden brown and potatoes are hot. Tent with aluminum foil during cooking if browning too quickly.

Microwave Reheating Method

  • Uncover casserole and microwave on high for one minute intervals. Stir after each additional minute, until potatoes are hot.


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