Special equipment: 2 (9-inch) square cake pans
Preheat the oven to 425 degrees F. Spray the cake pans with nonstick cooking spray and set aside.
In a large mixing bowl, combine the cornmeal, flour, sugar, baking powder, baking soda, salt, and cayenne.
In a separate bowl, whisk together the buttermilk, eggs and the butter. Mix the wet ingredients into the dry, stirring until well combined. Fold in the Cheddar, and salsa, and divide the batter between the 2 pans.
Place in the top half of the oven and bake for 30 minutes, until the center is firm to the touch and top is golden. Remove from oven, let cool and slice.