Pour bag in mixer. Add butter, egg, buttermilk, and vanilla and mix well.
Let batter rest for 15 minutes and mix again to fully hydrate gluten-free flour.
Gently fold in by hand any mix-ins like dried fruit, nuts, etc.
Shape batter into a disk and place on parchment lined sheet or silicone baking mat. Cut into 8 triangles.
Brush with cream and sprinkle with course sanding sugar.
BAKE
Bake at 350° for 18-20 minutes. Take out of oven and place them in a covered container right away. This will help them retain the moisture. Store in container and keep on counter 1-2 days or in refrigerator for 3-5 days.