Make-Ahead Mashed Potato Casserole

Thanksgiving day can be a real hassle preparing all the sides, but this make-ahead mashed potato casserole can take some of your troubles away.  Prep this mashed potato casserole the day before, put it in the fridge, then stick it in the oven for 45 minutes on Thanksgiving Day, and enjoy a perfect potato dish for your homemade gravy.

No more heating up the kitchen, boiling potatoes, then having to mix them up while your guests are waiting for Thanksgiving dinner.  All the hard work is done and the onion-infused mashed potatoes will be a hit.  The flavor of this make-ahead potato casserole is fantastic.

Our Thanksgiving dinner is full of side dishes. Sweet potatoes, creamy string beans with crunchy fried onions, two kinds of cranberry sauce, and of course, lots of dressing.  Having the healthy potato casserole ready to slide into the oven is a definite plus.  And the mashed potatoes are an integral part of the whole meal so they have to be good.

Putting the Mashed Potato Casserole Together

Mashed potatoes can be kind of bland, but these potatoes are really kicked up with some softened onions that get pureed and mixed in with vegetable broth, half and half, butter, and eggs to hold it all together.  The best thing is that they are made the day before, put in a casserole dish, and then store the prepared mashed potatoes in the refrigerator overnight.

The make-ahead mashed potatoes are ready to be warmed up the next day. Take the casserole out of the refrigerator about an hour before you bake it to let it warm up a bit. Take a spoon or fork to lift up some nice peaks that will brown in the oven. Place the dish in a 350° F oven for around 45 minutes and it should be heated through and ready to serve.

This makes not only an easy side dish but one that looks fabulous with a nice crust and creamy insides.  Your guests will be impressed with the look and amazed by the flavor.

Serve make-ahead potato casserole with turkey, ham, pork roast, or beef. It’s perfect for any meal. 

Have a great happy and safe holiday season.

Be sure to try these tasty recipes:

• Creamy Potato Leek Soup
• Orzo Chicken Casserole
• Cranberry Quick Bread
• Caramelized Onion Mashed Potatoes

Make-Ahead Mashed Potato Casserole

This is an easy way to prepare mashed potatoes for Thanksgiving Day!

4.5 from 6 votes

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Course: Potato side dish

Cuisine: American

Keyword: healthy potato casserole, make-ahead mashed potato casserole, mashed potato casserole

Prep Time: 20 minutes

Cook Time: 1 hour 30 minutes

Total Time: 1 hour 50 minutes

Servings: 10 servings

Calories: 269kcal

Author: Joe Boyle

Ingredients

• 4 lbs. russet potatoes, peeled and cut into 1 inch pieces (8 or 9 medium to med-large potatoes)
• 2 yellow onions, coarsely chopped about 2 cups
• 1 tbsp vegetable oil
• 2 garlic cloves, coarsely chopped
• 3/4 cup vegetable broth, (I use Better than Bouillon, seasoned veg. base, 1 1/2 tsp.)
• 1/2 cup half and half
• 8 tbsp butter
• 1/4 cup chopped scallions, green parts only
• 3 eggs
• 1 1/2 tsp salt
• pepper, if desired

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Instructions

• Place potatoes in a large sauce pan or stock pot with water and 1 tsp salt. Bring to a boil and cook until soft, 15 to 20 minutes.
• While the potatoes are cooking, place chopped onions and 1/2 tsp salt into a skillet with the vegetable oil and cook on low heat until the onions have softened,  5 to 7 minutes.
• In a small saucepan, melt the butter, then add the half and half and 1 cup of the vegetable broth, keep warm.
• Once the onions are done, place them into a food processor along with the garlic and the remaining vegetable broth. Chop until the onions are finely chopped.
• Drain the potatoes, add the onions and the melted butter with the liquids. Use a hand mixer to mash them until they are smooth.  Let the potatoes cool. (I put 4 inches of cold water in the sink and placed the pot into it for 15 minutes).
• Add the eggs one at a time and mix them in. (Alternatively, you could use 4 to 6 ounces of softened cream cheese rather than the eggs.  The eggs give the potatoes an airy lift while the cream cheese would not.  Both would be equally good).  Taste the potatoes and adjust salt and pepper seasoning.
• Add the scallion greens and fold in with a spoon or spatula.
• Spray cooking oil in a 3 quart casserole dish and add the mashed potatoes. Cover with plastic wrap and store in the refrigerator overnight.
• Take the potatoes out of the refrigerator at least one hour before placing in the oven.  Use a spoon or fork to make peaks, then place into a 350 degree oven for 45 minutes until the potatoes are warm and the peaks are starting to brown. (If you make this the same day, allow 30 to 35 minutes in the oven).
• Serve hot.

Notes

1. Adapted from Cook's Country.
2. Leftover mashed potatoes can be kept in an airtight container in the refrigerator for 3 days. Reheat in a microwave.

Nutrition

Calories: 269kcal

Here are a couple more recipes to consider for Thanksgiving

Red Wine Cranberry Sauce

Sweet Potato and Caramelized Onion Skillet

This recipe post has been updated on December 19, 2021.