Preheat the oven to 350°F. Lightly grease a 9x13-inch baking dish.
In a medium bowl, mix together the whole milk, sour cream, melted butter, eggs, and creamed corn until smooth and uniform.
In a large bowl, whisk together the cornmeal, all-purpose flour, sugar, baking powder, baking soda, and salt until well combined.
Pour the wet ingredients into the dry ingredients and stir with a spatula or wooden spoon just until combined and no dry streaks remain. Do not overmix.
Gently fold in the chopped jalapeño peppers and shredded cheese until evenly distributed. If using, fold in the corn kernels.
Scrape the batter into the prepared baking dish and smooth the top with a spatula.
Bake until the top is golden and the edges are set and pulling slightly away from the pan, about 30-40 minutes. A toothpick inserted in the center should come out clean or with a few moist crumbs.
Transfer the pan to a wire rack and let the cornbread cool for 5-10 minutes.
Slice and serve warm.