Heat oven to 400º F. Lightly coat a baking sheet with vegetable cooking spray.
In a food processor, combine the flour, baking powder, and butter and pulse until the mixture resembles coarse breadcrumbs. Transfer to a large bowl and add the 2 cheeses, thyme, hot pepper flakes, and buttermilk. Stir until the mixture sticks together. (It will be slightly crumbly.)
Transfer the dough to a work surface and knead gently until it comes together, about 30 seconds. Shape the dough to form an even, flat round about 1 inch thick. Cut the dough into 12 wedges. Place them about 2 inches apart on the baking sheet.
Bake until the scones are light golden brown, 18 to 20 minutes. Remove with a metal spatula. These are best served fresh but can be made up to 2 days ahead. Wrap in foil and reheat in a 250º F oven for 10 minutes. Store in an airtight container.