This post is sponsored by Vidalia Onions.  All opinions are my own.

Vidalia Onions and Potato Au Gratin

I have been cooking up a storm lately; I’ve been cooking a lot of comfort foods and some favorites that I don’t make often enough.   One of my favorite dishes which I don’t make nearly enough is potato au gratin.  I decided to kick it up a notch and make a Vidalia Onion and Potato Au Gratin instead and it was a hit!

Vidalia Onions and Potato Au Gratin Vidalia Onions and Potato Au Gratin

This dish is made by layering potatoes, Vidalia onion and baking it in a creamy cheese sauce.  Vidalia Onions, which are available for a limited time from April to August, is a sweet variety of onions that are a great addition to any savory dish.  Vidalia Onions are hand planted and only grown in 20 counties in South Georgia.  I remember driving past some of the fields on the way to Savannah! What I love about this dish is that it’s delicious and easy to make.  I will share a few tips and tricks that will help if this is your first time making any type of au gratin. 

Vidalia Onions and Potato Au Gratin Vidalia Onions and Potato Au Gratin

Tips and Tricks:

  • Cut the Vidalia Onions into thick slices, about ¼ inches in thickness and layer between the potatoes.
  • The best potatoes to use are Yukon gold or red potatoes. They both hold their shape as they cook.  Yukon gold potatoes are my favorite to use because of its silky texture when cooked.
  • Sharp cheddar cheese or any bold cheese is great in this dish. Yellow or white cheddar, gruyere or smoked Gouda works well.
  • Making a roux prevents the cheese sauce from curdling.
  • Heavy cream, full fat milk or part skim milk can be used.
  • Nutmeg can be added for additional flavor.

Vidalia Onions and Potato Au Gratin Vidalia Onions and Potato Au Gratin

Yield: 4

Vidalia Onion and Potato Au Gratin

Vidalia Onions and Potato Au Gratin
Prep Time 15 minutes
Cook Time 1 hour
Total Time 1 hour 15 minutes


  • 1 large Vidalia Onion, cut into slices about ¼ inch thick
  • 2 lbs Yukon Gold Potatoes, thinly sliced
  • 3 tbsp butter
  • 3 tbsp flour
  • 1 cup milk
  • 3 sprigs thyme
  • ½ tsp garlic powder
  • ½ tsp black pepper
  • ½ tsp salt
  • 1 cup grated sharp cheddar or gruyere cheese


In a small pot over low heat melt butter.  Add flour and whisk smooth and cook for about
2 minutes.  Add milk and cook until sauce
has thickened, about 3-5 minutes.

Stir in garlic powder and grated cheese.  Remove from heat.

Brush a 8 x 8 baking dish with butter.  Place half of the potatoes in one layer and
then top with half of onion slices, thyme leaves, salt and black pepper.  Top with half of cheese sauce.

Layer remaining half of potatoes and onion, thyme leaves,
salt and black pepper then top with the rest of the cheese sauce.  Sprinkle grated cheese on the top.

Cover dish with foil and place into an oven preheated at 350
degrees and bake for 45 minutes covered.  
Test the potatoes to see if tender, then remove foil and bake for an
additional 15 minutes or until golden brown.

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