2 pounds assorted petit fingerling potatoes (including Purple Peruvian, Marble, Russian banana and red skinned), well washed
Salt
Olive oil, as needed
5 sprigs thyme
1 head garlic, split
1 1/2 sticks butter
1 pound fingerling potatoes, peeled
1 1/2 cups heavy cream
1/2 cup half-and-half, or as needed
1 ounce aged Gruyere, grated
1 1/4 teaspoon creme fraiche
Salt