Start by dicing the cold unsalted butter into 1/4-inch cubes. Place the diced butter in the freezer while you prepare the other ingredients.

In a stand mixer bowl, combine all-purpose flour, granulated sugar, kosher salt, baking powder, baking soda, freshly ground black pepper, minced sage, and grated Gruyere cheese until well mixed.

Add the cold butter to the dry ingredients. Blend the mixture until it resembles clumpy sand with small butter pieces still visible.

Gradually mix in buttermilk and heavy cream, stirring just until a shaggy dough forms. Be careful not to overmix.

On a floured surface, shape the dough into an 8x11-inch rectangle. Fold it like a letter into thirds. Roll it out again and repeat this folding process three more times, then cut into a 9-inch square.

Cut the dough into squares or circles and place them on a parchment-lined baking sheet. Pop the cut biscuits into the refrigerator to chill for 45 minutes.

Preheat your oven to 450°F. Brush the tops of the chilled biscuits with heavy cream, sprinkle with flaky salt, and bake for 18-20 minutes until they're puffed up and golden brown.