Preheat your oven to 400°F. Cut off the top quarter-inch of the garlic head (just the pointed top where the cloves meet) and discard. Place the garlic head on a piece of aluminum foil, drizzle with the olive oil, and wrap the foil around it completely, sealing it well.

Roast the garlic for 30-40 minutes until it's completely soft and golden. You can tell it's done when a knife slides through the cloves easily. Set aside to cool slightly while you work on the potatoes.

While the garlic roasts, peel your Yukon Gold potatoes and cut them into even 1-inch chunks. Try to keep them relatively uniform so they cook at the same rate.

Place the diced potatoes in a large pot and cover with cold salted water. Bring to a boil over medium-high heat, then reduce to medium and simmer for 30-35 minutes until completely fork-tender. The potatoes should break apart easily when pierced.

While the potatoes cook, make your brown butter sage. Add the 10 tablespoons of butter and the 2 sage sprigs to a saucepan over medium heat. Watch it carefully – you're looking for the milk solids in the butter to brown and create a nutty aroma.

Once the butter turns golden brown (about 5-7 minutes), remove it from the heat and take out the sage sprigs with tongs. Set the brown butter aside – the sage flavor is already infused in it, and you don't need the sprigs anymore.

When the potatoes are fork-tender, drain them thoroughly in a colander. Don't skip this step – excess water will make the potatoes gluey.

Transfer the drained potatoes to a stand mixer fitted with the paddle attachment (or use a large bowl and hand masher). Mash until they're mostly smooth, leaving just a few tiny chunks if you like.

Add 8 tablespoons of the brown butter, the roasted garlic (squeeze the soft cloves right out of their papery shells), the heavy cream, salt, and pepper to the mashed potatoes.

Mix on medium speed until completely smooth and creamy, about 2-3 minutes. Don't overmix or you'll end up with gluey potatoes – stop as soon as everything is combined and smooth.

Transfer to a serving dish and top with the remaining 2 tablespoons of brown butter, letting it melt over the top for a beautiful, rich finish.