Preheat your oven to 400°F (200°C) to ensure even baking.
In a large mixing bowl, whisk together the sour cream, milk, and eggs until smooth.
Pour in the melted salted butter and stir until fully combined.
Add the two boxes of Jiffy corn muffin mix to the wet ingredients and gently stir until just combined.
Fold in the chopped pickled jalapeños, thawed corn, and 1 cup of shredded sharp cheddar cheese.
Grease your 9x13-inch baking dish and pour the cornbread batter into it, spreading it evenly.
Sprinkle the remaining 1/2 cup of shredded cheddar cheese on top and arrange the thinly sliced jalapeño.
Place the baking dish in the preheated oven and bake for 20-25 minutes, or until golden brown.
Once baked, remove from the oven and allow it to cool for a few minutes before slicing.
