1. Preheat oven to 450°.
2. Weigh or lightly spoon flours into dry measuring cups; level with a knife. Combine flours, baking powder, sugar, salt, and baking soda in a large bowl, stirring with a whisk to combine.
3. Place butter in a microwave-safe bowl. Microwave at HIGH for 1 minute or until completely melted. Add cold buttermilk, stirring until butter forms small clumps. Add oil, stirring to combine.
4. Add buttermilk mixture to flour mixture; stir with a rubber spatula until just incorporated (do not overmix) and batter pulls away from sides of bowl. (Batter will be very wet.)
5. Drop batter in mounds of 2 heaping tablespoonfuls onto a baking sheet lined with parchment paper. Bake at 450° for 11 minutes or until golden. Cool 3 minutes; serve warm.