Mixed Potato Gratin

This is a combination of Yukon Gold Potatoes and Sweet Potatoes in a Gruyere and Parmesan Cheese Gratin.  It's made in a shallow 2 quart casserole dish.
We have a French friend that made this without the Sweet Potatoes. You can do this too by just replacing the Sweet Potatoes with additional Yukon Gold Potatoes. However, I like the combination of the two.
What a great addition this would be to your Thanksgiving Menu.

Here's what you'll need:
Preheat the oven to 375 degrees.
Heavily Butter a shallow 2 Quart Casserole Dish.

Half of a Vidalia Onion, diced
1 TBS Butter
1 TBS Olive Oil
1 3/4 C Heavy Cream
2 TBS Fresh Chopped Parsley
1 TBS Fresh Chopped Chives
1 tsp Fresh Chopped Rosemary
1/2 tsp Pepper
1/4 tsp Salt
1/8 tsp Nutmeg
5 Yukon Gold Potatoes, peeled and sliced thin on a Mandoline.
4 Sweet Potatoes, peeled and sliced thin on a Mandoline.
2 C Whole Milk
2 C Shredded Fresh Gruyere Cheese
1/2 C Grated Parmesan Cheese
2 TBS Butter, cubed.


In a saucepan on medium high heat:
Heat Butter and Olive Oil
Add:
Onions
Saute until soft.

Add:
Heavy Cream
Parsley
Chives
Rosemary
Pepper
Salt
Stir and continue sautéing for 2 minutes, stir well.
Set aside to cool completely.

In a large glass mixing bowl that's microwave safe:
Yukon Gold Potatoes
Sweet Potatoes
Toss to mix together.

Add:
Whole Milk, not the Cream mixture!
Toss with your hands to coat everything.
Cover with plastic wrap and heat in the microwave for 5 minutes.
Stir the Potatoes and continue heating, covered for an additional 5 minutes.
Drain the Potatoes and discard the Liquid.

Spoon 1/2 of the Potato mixture into the Casserole Dish.
Add:
1/2 of the Heavy Cream Mixture.
Sprinkle evenly with 1/2 of the Gruyere Cheese and 1/2 of the Parmesan Cheese.
Repeat with remaining Heavy Cream, Gruyere Cheese and Parmesan Cheese.
Dot evenly with cubed Butter.
Cover with Aluminum Foil.
Bake for 30 minutes.
Uncover the casserole and continue baking for 20 - 30 minutes.
The top should be Golden Brown.

Enjoy!
Peace in the Kitchen!