Preheat oven to 375°. To prepare the shortcakes, lightly spoon flour into dry measuring cups; level with a knife. Combine flour, sugar, unsweetened cocoa, baking soda, baking powder, and salt in a large bowl, stirring with a whisk. Cut in 1/4 cup butter with a pastry blender or 2 knives (or your hands) until mixture resembles coarse meal. Add buttermilk; stir just until moist. Knead lightly in bowl 5 to 6 times. Turn dough out onto a lightly floured surface; pat dough into an 8-inch circle on a baking sheet lined with parchment paper. Cut dough into 8 wedges, cutting into, but not through, dough. Bake at 375° for 18 minutes or until just firm to the touch. You can poke with a toothpick to make sure wet dough doesn't come out. Avoid overcooking or they will become quite crumbly. Remove from pan; cool on a wire rack. Place shortcake on a cutting board or work surface; cut along score lines with a serrated knife to form 8 wedges. When ready to serve, slice cakes in half horizontally (be gentle, they'll break easily if manhandled too much) and fill with 1/4 c. sliced bananas, 2 Tbsp. whipped topping (a cookie dough scoop works great), and a little caramel sauce (about 1 teaspoon). Replace top layer of the shortcake and then drizzle with an additional caramel sauce.