Preheat your oven to 425 degrees. Grease a pie tin with butter or lard.
Thoroughly whisk the flour, cornmeal, baking powder, and salt together (it's best to whisk your dry ingredients with a wire whisk). Add the butter, jalapenos, and cheese and cut in with a pastry cutter until it has a pebbly texture. Do not overwork it.
Add the buttermilk, stirring with a spoon until everything is moistened, but not overworked.
Turn the dough out onto a lightly floured surface. Press into a ball, then roll out to about 3/4-inch think with your rolling pin. Use a 2 1/2-inch biscuit cutter to cut out your biscuits. Place in the pie tin where they are barely touching, or there is a little space in-between, but not smashed together.
Bake on the center rack for 12-14 minutes, until golden brown on top. If you want the tops lightly browned, turn your broiler on high for the last 3-4 minutes. When done, remove from the oven and brush immediately with melted butter. Let rest for 10 minutes before enjoying.