Prepare the Corn: Remove the husks and silk from the corn. Pat the ears dry with a clean kitchen towel. If using frozen corn kernels instead, thaw them and pat them dry before cooking.
Mix the Creamy Sauce: In a small bowl, combine the mayonnaise, sour cream, lime juice, chili powder, and smoked paprika. Stir until smooth and set aside.
Heat the Grill or Skillet: Preheat an outdoor grill to medium-high heat, or heat a large skillet over medium-high heat. If using a skillet, add the optional butter once the pan is hot.
Cook the Corn: Place the corn on the grill or in the skillet. Cook for 10–15 minutes, turning every few minutes, until the kernels are tender and develop golden-brown charred spots. If using a skillet, cook in batches if necessary.
Apply the Sauce: Transfer the hot corn to a serving plate. While it is still warm, spread the creamy sauce over each ear, coating the kernels evenly.
Add the Cheese: Sprinkle the crumbled cotija cheese over the coated corn. Gently press the cheese onto the surface so it adheres to the sauce.
Garnish with Fresh Herbs: Scatter the chopped cilantro over the corn. Add an extra pinch of chili powder or smoked paprika if you prefer a stronger seasoning.
Serve with Lime: Finish with a squeeze of fresh lime juice and serve immediately while the corn is warm. Provide extra lime wedges on the side for anyone who wants more tanginess.