How to Make It
Preheat oven to 400°F.
Peel away the outermost layers of papery skin from the head of garlic, leaving the head intact. Trim a small amount (about ¼ inch) off the top of the head of garlic, exposing the garlic cloves inside. Place the head on a sheet of aluminum foil; drizzle with 1-2 teaspoons olive oil. Fold up the sides of the aluminum to create a sealed packet. Roast in the oven for 40-50 minutes, or until all cloves are golden-brown and are tender when pierced with a knife. Cool slightly.
Place 10 tablespoons of the butter in a small mixing bowl. Squeeze the contents of each garlic clove into the bowl. Mash and stir the garlic into the butter until well dispersed. Transfer the roasted garlic butter to a sheet of wax paper or parchment paper. Wrap the butter and place in the fridge until re-solidified and hard, about 2 hours.
Preheat oven to 425°F.
In a large mixing bowl, whisk together the flour, baking powder, baking soda, sugar, and salt. Combine the sour cream and milk in a glass mixing cup or small mixing bowl, stir with a fork until combined.
Cut the roasted garlic butter into small pieces and scatter over the flour mixture; toss to coat. Work the butter into the flour mixture using your fingertips until butter is thoroughly distributed and pea-sized clumps form.
Form a well in the center of the mixture and add the sour cream and milk mixture. Stir until a shaggy dough forms. With floured hands, gently knead the dough a couple of times in the bowl to bring everything together.
Turn the dough out onto a lightly floured surface. Pat the dough into a rectangle (about 7”x4”); the dough should be about 1-inch-thick. Fold the rectangle into thirds, folding one short side of the dough rectangle into the center and repeating with the remaining short side of dough (this third will fold over the first short side). Gently pat the dough back out into a rectangle, roughly the same size as the first. Repeat the folding and patting process once more.
Once you’ve patted the dough back into a rectangle for the final time, use a sharp knife or bench scraper to cut the rectangle in half horizontally. Then, cut the rectangle vertically into 4 even pieces, ultimately forming 8 biscuits. Transfer the biscuits to a parchment paper lined baking sheet, placing them 2 inches apart.
Melt the remaining 2 tablespoons butter in the microwave or on the stovetop. Brush the biscuits evenly with butter and sprinkle with flakey sea salt. Bake 20 minutes or until golden brown.
Make Ahead Tip: You can make the roasted garlic butter a day (or a few days) in advance so that actually making the biscuits is more streamlined.