"This is the result of combining a number of my favorite cornbread recipes. The first time I made it I had people begging for the recipe -- the problem was that it didn't exist, as I had just improvised it as I went along. Here's my attempt to put it down in words"
Cook the bacon. Remove once cooked, let cool, and then crumble. If you are using a cast-iron skillet, cook the bacon in it, and reserve the grease in the pan (though you can drain some of it if it's excessive).
Place the skillet, with the grease in it, in the oven while it is preheating.
While the bacon is cooking, combine the flour, cornmeal, sugar, baking powder, and salt in a large bowl.
In separate bowl, combine the milk, buttermilk, eggs, and melted butter.
Stir the wet ingredients into the dry until most of the lumps are dissolved (don't overmix).
Fold in the cheese and diced jalapenos.
Let the mixture sit for about 10 minutes at room temperature.
Pour the batter into the hot skillet (or a greased baking pan).
Sprinkle the crumbled bacon on top and press it in gently.
Bake for 30-35 minutes, until a toothpick comes out mostly clean.
Remove from the pan/skillet on to a cooling rack, and let it rest at least 10 minutes before slicing.