Sharp cheddar, roasted red pepper, and jalapeños are all it takes to make these cheesy biscuits.
In a large bowl, whisk 2 cups flour, the baking powder, baking soda, and salt. Turn the stick of butter in the dry ingredients until coated. Using the large holes on a box grater, grate the butter into the bowl. Using your fingertips, evenly mix in the butter. Mix in extra-sharp cheddar, roasted red peppers, cornmeal, and chopped jalapeño. Form a well in the dry ingredients.
In a small bowl, whisk the sour cream and 1/3 cup very cold water. Pour into the dry ingredients and stir just until blended. Cover and refrigerate for at least 20 minutes or up to 4 hours.
Position a rack in the center of the oven; preheat to 450°. Grease a large baking sheet. Transfer the dough to a floured work surface and pat into a circle about 1 inch thick, dusting with more flour if the dough is sticky. Using a 2-inch cutter, cut out biscuits, pressing straight down into the dough (do not twist). Transfer to the sheet. Gather the dough and repeat patting and cutting until the dough is used up. Arrange thinly sliced jalapeños on top.
Bake until the biscuits are golden and crispy on top, 12 to 15 minutes. Let cool for 5 minutes.
Butter It Up: In a mini food processor, puree butter and roasted red peppers; season.