Adjust oven to rack to middle position and heat oven to 180oC/350oF. Grease 8 1/2 by 4 1/2 inch loaf pan, then sprinkle 1/2 cup parmesan evenly in the bottom of the pan.
Whisk flour, baking powder, salt, pepper, and cayenne pepper together in large bowl. Stir in cheddar, breaking up clumps until cheese is coated with flour. Add in
Stir in cheddar, breaking up clumps until cheese is coated with flour.
Stir in the diced jalapenos.
Make a well in the center of your dry ingredients.
Add in the milk, egg, sourcream, and melted butter. Using a rubber spatula stir together with the dry ingredients, just until the flour is incorporated. Batter will be heavy and thick, do not overmix.
Transfer batter to the prepared pan and smooth top. Sprinkle remaining 1/2 cup parmesan evenly over the top.
Bake loaf until golden brown and skewer inserted in the center comes out clean, about 45 to 50 minutes, rotating the pan halfway through baking.
Let the loaf cool in the pan for about 15 minutes. Remove the loaf from the pan and allow to cool completely on a wire rack about 3 hours before serving.