Whisk together flour, sugar, baking powder, and salt in a large bowl.
Add butter to the bowl and cut into the flour with a pastry blender until the largest pieces of butter are about the size of a pea and the flour mixture resembles a coarse meal.
Stir in 3/4 cup of heavy cream and vanilla extract. If using the optional ingredients of an egg or add-ins, stir them in at this step as well.
Press dough together between the palms of your hands. If it doesn’t just hold together, add more heavy cream until it just holds together.
Pour the dough onto a lightly floured countertop or a pastry board. Pat the dough into a large round disc about an inch thick.