Preheat oven to 350 F. In a large bowl, whisk together flour, cornmeal, sugar, baking powder and salt. Whisk in milk, vegetable oil, diced pickled jalapenos, and shredded cheddar cheese.
Spoon cornmeal mixture into 12 greased muffin tins. Top each with a pickle jalapeno slice. Bake for 15-20 minutes.