Step 1: Preheat your oven to 425°F (220°C). Lightly grease a baking sheet or line with parchment paper.
Step 2: In a large bowl, whisk together the all-purpose flour, baking powder, and salt until well combined.
Step 3: Pour in the cold heavy cream and the chilled 7 Up soda into the dry ingredients. Stir gently with a spoon or your hands until just combined. The dough will be sticky, but avoid overmixing.
Step 4: Turn the dough out onto a lightly floured surface. Gently pat the dough into a rectangle about 1/2 to 3/4 inch thick. Do not knead or roll vigorously.
Step 5: Using a 2-inch biscuit cutter (or the rim of a glass), cut out biscuits. Press straight down without twisting the cutter to ensure a good rise. Gather scraps, gently re-pat, and cut any remaining biscuits.
Step 6: Place the cut biscuits onto the prepared baking sheet, either touching for softer sides or slightly spaced apart for crispier edges.
Step 7: Bake for 12-15 minutes, or until the biscuits are golden brown on top and cooked through. Baking time may vary depending on your oven.
Step 8: Once baked, remove the biscuits from the oven. If using, immediately brush the tops with melted butter for extra flavor and a beautiful sheen. Serve warm.