Heat the oven to 400°F and set a rack in the center position.

Set a 10-inch oven-safe skillet over medium-high heat and melt the butter. Add the corn kernels in an even layer and let them sit without stirring for 3 minutes, then stir and cook 5 to 7 minutes more, until many kernels show dark brown charred spots and smell toasted.

Stir in the jalapeno and garlic and cook for 1 minute, until fragrant. Scrape the entire corn mixture into a large white mixing bowl and let it cool for 5 minutes so it does not melt the cream cheese.

In the same bowl, add the softened cream cheese, mayonnaise, and sour cream. Beat with a wooden spoon or hand mixer until the mixture turns smooth and pale, with no streaks of cream cheese left.

Add half of the cotija, half of the Monterey Jack, the chili powder, smoked paprika, cayenne (if using), lime zest, lime juice, cilantro, salt, and black pepper to the bowl. Fold everything together until the corn is evenly coated and the mixture looks uniformly creamy and speckled with corn and herbs.

Scrape the mixture back into the same skillet, spreading it into an even layer. Scatter the remaining cotija and Monterey Jack over the top so the surface is fully covered.

Bake, uncovered, for 20 to 22 minutes, until the edges bubble visibly and the cheese on top turns melted and lightly golden in spots.

Remove the skillet from the oven and let the dip rest for 5 minutes so it firms up slightly and is easier to scoop without scalding anyone's mouth.

Scatter extra cilantro and a pinch of chili powder over the top and serve the skillet warm, with a stack of tortilla chips alongside for scooping.