Preheat oven to 400°F. Spray a baking sheet with nonstick spray.
Put the flours, sugar, baking powder, baking soda and salt in the bowl of a food processor or into a medium mixing bowl and pulse or stir until well blended. Add the butter and oil and pulse or stir with a wire whisk or fork until crumbly. If you’re using a food processor, transfer the mixture to a medium bowl.
Add the milk and stir gently until the dough begins to come together. Add any additions (cheese, raisins, nuts, fruit etc.) as you stir the dough together.
For wedge-shaped biscuits, pat the dough into a circle that is about 1” thick and 8”-9” in diameter on the cookie sheet. (If they are sweet and you want a brown, crunchy top, brush them with a little milk and sprinkle with sugar.) Cut the circle into 8 wedges with a knife or pastry cutter and separate them on the sheet so that they are at least an inch apart. For round biscuits, pat the dough about 1” thick and cut it into rounds with a biscuit cutter, glass rim or open end of a can, rerolling the scraps only once to get as many biscuits as possible.
Bake for about 20 minutes, until golden. Serve warm. Wrap well and freeze any you don’t eat the same day.