Roast the garlic heads: Preheat your oven to 400°F (200°C). Slice 1/4 inch off the top stem of both whole garlic heads to expose the cloves. Drizzle with 1 tablespoon of olive oil and wrap tightly in aluminum foil. Roast for 40 to 45 minutes until the cloves are golden amber, completely tender, and sweetly caramelized. Allow to cool slightly, then squeeze the soft cloves into a small bowl and mash into a smooth paste with a fork.

Boil the potatoes evenly: Place the peeled, evenly cut Yukon gold potatoes in a large heavy pot. Cover with cold water by at least 1 inch and stir in 1.5 tablespoons of sea salt. Bring to a boil over medium-high heat, then reduce to a steady simmer for 15 to 18 minutes until a paring knife glides through effortlessly with zero resistance. Drain thoroughly in a colander.

Steam-dry the potatoes (Chef Secret): Return the drained hot potatoes back into the empty warm pot over very low heat for 1 to 2 minutes, shaking gently. Evaporating all residual cooking water guarantees your potatoes will greedily absorb rich melted butter and cream rather than water.

Brown the European butter: While the potatoes steam-dry, melt 3/4 cup of European unsalted butter in a medium skillet or light-colored saucepan over medium heat. Swirl occasionally as it melts, foams vigorously, and begins to crackle. After 4 to 5 minutes, the foam recedes and milk solids turn golden brown with an intoxicating nutty, hazelnut aroma. Drop in the fresh sage leaves for 30 seconds until crisp, then immediately remove from heat to prevent burning. Set aside 2 tablespoons of browned butter and the crispy sage for garnish.

Rice the potatoes to cloud-like silkiness: Pass the hot potatoes through a potato ricer or food mill directly into a large mixing bowl (or mash thoroughly with a heavy masher). Never use a food processor or electric mixer, which shears starch cells and creates gummy glue.

Fold in garlic, brown butter & cream: While the riced potatoes are piping hot, gently fold in the roasted garlic paste, warm heavy cream, mascarpone cheese, and the remaining browned butter (along with all those flavorful toasted brown specks). Gently whip with a wooden spoon or silicone spatula just until velvety, silky smooth, and thoroughly incorporated. Season to taste with sea salt and cracked white pepper.

Swirl, crown & serve hot: Spoon the luscious mashed potatoes into a warm ceramic serving bowl. Use the back of a spoon to create elegant deep swirls across the surface. Pour the reserved 2 tablespoons of warm foamy brown butter directly into the wells, crown with crispy fried sage leaves, snipped chives, and a pinch of flakey Maldon sea salt. Serve immediately with warm gravy!