Preheat the oven to 425 degrees . In a large bowl, stir the corn muffin mix, milk, egg and jalapeno until just combined.
Brush the bottom and sides of a large cast-iron skillet with 1 tbsp. oil; heat over high. Add the sweet potatoes and onion; season with salt and pepper. Cook, stirring often, until the vegetables soften, about 3 minutes; transfer to a medium bowl.
In the same skillet, heat the remaining 1 1/2 tsp. oil over medium-high. Add the beef, season and cook until browned, about 3 minutes. Off heat, stir in the tomatoes and their juices, the corn, cilantro, chipotle, adobo sauce and the sweet potato mixture; season.
Spread the mixture evenly in the skillet; top with the muffin batter, leaving a 2-inch border. Bake until the cornbread is golden and a tester inserted in its center comes out clean, 15 to 18 minutes.