Step 1

Heat oven to 375.

Step 2

I like using Yukon gold for mashed potatoes because I can get away with not peeling the potatoes. Dice the potatoes and place in a large pot filled halfway with cold water.

Step 3

Add 3 tablespoons kosher salt.

Step 4

Bring to a boil, then reduce heat and simmer until the potatoes are tender.

Step 5

Meanwhile, gently heat the milk, cream, garlic, peppercorns, bay leaves, and sprig of thyme in a small saucepan over medium heat. Don’t let the mixture boil.

Step 6

Once the mixture is very hot, take off heat and let the aromatics infuse the milk for 20 minutes.

Step 7

Strain out the aromatics using a slotted spoon.

Step 8

Mash the cooked potatoes with the butter and infused milk.

Step 9

Stir in chopped chives.

Step 10

Grease an 8 x 8 baking pan and a 9 x 13 pan.

Step 11

Spread the mashed potatoes evenly into the prepared pans.

Step 12

Whip the 2 ½ cups cream using an electric mixer.

Step 13

Spread the whipped cream over the potatoes, and top with the cheddar and parmesan cheeses.

Step 14

Bake for 45 minutes, or until the top gets a nice golden brown color.