500 g yellow fleshed potatoes, peeled and quartered
1 sprig thyme
1 cloves garlic, finely minced
3 tablespoons (45g) unsalted butter
1/2 cup (125ml) 35% cream
325 g Tomme d’Auvergne cheese, grated (or 200 g Gruyere and 125 g fresh mozzarella or fontina)
Place potatoes and thyme in a medium saucepan covered with 1-½-inches (4cm) of water. Liberally salt water and bring to a boil over high heat. Cook until potatoes are fork tender, about 20 to 25 minutes.
Combine garlic, butter and heavy cream in a small saucepan and heat gently over low heat for 15 minutes.
Drain potatoes and discard the thyme. Pass potatoes through a ricer or a food mill back into saucepan. Add cream mixture and place over medium-low heat and stir the mixture together with a wooden spoon. Gradually add in grated cheese a handful at a time until mixture is stringy and thick. Season with salt.