Add the flour, cornstarch, baking powder, and salt to the bowl of a food processor. Pulse 5-10 times, or until well combined.
1¾ cups all purpose flour, ¼ cup cornstarch, 1 tablespoon baking powder, ½ teaspoon kosher salt
Add the cubed butter and pulse until the butter is the size of peas, about 10 pulses.
½ cup unsalted butter
In a large bowl, whisk the heavy cream and 1 egg together Add the butter-flour mixture to the wet ingredients and mix until the dough begins to come together into large clumps. If using any add-ins, add them to the dough now.
¾ cup heavy cream, 2 large eggs, 1 cup shredded cheddar cheese
Turn the dough out onto a lightly floured surface and shape it into an 8-inch round circle. It may look dry at first, but keep working it with your hands and it will come together! Cut the dough into 8 triangles.
Place the scones on a parchment-lined baking sheet, making sure to place them at least 2 inches apart. They will spread a little while baking.
Place the scones in the freezer to chill for 30 minutes. While the scones chill, preheat your oven to 350°F.
When the oven is fully preheated, brush the scones with the remaining egg whisked with a splash of water to create an egg wash. Bake for 22-25 minutes, or until the scones are puffed and golden brown around the edges.
While the scones bake, make the garlic-chive butter: Mix the melted butter, garlic powder, and chives together. Brush the butter over the scones as soon as they come out of the oven. Sprinkle with flaky salt, if desired.
3 tablespoons unsalted butter, ½ teaspoon garlic powder, 1 tablespoon thinly sliced chives, Flaky sea salt
Allow the scones to cool completely before enjoying.