From the Rumford Baking Powder can comes this brilliant and quick little cornmeal biscuit. Slice and stack the dough just like a butter fan roll, slap it in a muffin tin, and it bakes up into a pretty tiered shape. —Posie (Harwood) Brien
In a large bowl, whisk together the flour, cornmeal, baking powder, and salt.
Cut in the shortening until the mixture is crumbly and the shortening is in very small lumps.
Slowly add the milk and stir with a fork until the dough begins to come together. Start with just 1/2 cup of the milk -- you might not need all of the milk. The dough should be soft but not at all wet.
Turn the dough out onto a lightly floured surface and roll it out to a rectangle, 1/4-inch thick. It will be about 14" x 6", roughly. Be sure to keep dusting the dough and rolling pin with flour as you go to keep it from sticking.
Brush the surface of the rectangle with melted butter.
Cut the rectangle into long strips, about 1 1/2" wide. Stack 6 or 7 strips on top of each other, and then cut the stacks into 2" pieces. Place the 2" stacks into the wells of a greased muffin tin.
Brush the tops of the stacks with more melted better and sprinkle with flaky sea salt (optional!). Bake for about 12 minutes or until the tops just begin to brown.
Remove from the oven and let cool slightly, then eat warm!