Preheat oven to 425 degrees F (220 C). Set out a large cast-iron skillet, or line a baking sheet with parchment paper or a silicone baking mat; set aside.
In a large bowl or food processor, combine the flour, baking powder, and salt; whisk or pulse to blend. Add the cubed butter and pulse again, or cut the butter into the flour mixture with two knives or a pastry blender. You’re aiming for coarse, pebbly crumbs with visible bits of butter. If using a food processor, pour the mixture out into a large bowl.
Make a well in the center of the flour-butter mixture, and pour in 1 cup (240 ml) of buttermilk, followed by the honey. Fold just until combined - take care not to overmix. Add the grated cheddar and rosemary, and gently fold again. The dough will be quite crumbly - don’t worry, it will come together more as you shape it in the next steps.
Turn the dough out onto a lightly floured work surface and, using your hands, gently press it into a rough rectangle. Fold one third of the rectangle into the center, then fold the opposite third on top of it, as if folding a letter. (See photo in post for a guide.) Rotate the dough 90 degrees, then gently press it back into a wider rectangle.
Repeat the folding process, then turn the dough and flatten again, followed by one more round of folding. (You will have done the “letter” fold three times in all. This is what’s going to give you amazing, flaky layers!)
Using a rolling pin, gently roll out the dough until it’s about 1/2-inch thick. Using a biscuit cutter or a medium-sized glass, cut the dough into circles approximately 3 inches in diameter. Re-roll scraps to create additional biscuits. Arrange cut biscuits in your cast-iron skillet or lined baking sheets, being sure that their sides are touching.
Brush the tops lightly with the remaining buttermilk, and bake for 12-15 minutes, until the tops are golden brown.
Serve biscuits warm with additional butter, honey, or toppings of your choice. Wrap any leftovers in airtight packaging and store at room temperature or in the fridge for 3-4 days.