Insert wooden corn holders or skewers into each end of the corn ears for easy handling.
Heat a large cast iron skillet or grill pan over medium-high heat. Cook corn, turning every 2-3 minutes, until charred and golden brown on all sides, about 10-12 minutes total.
While corn is cooking, whisk together mayonnaise, Mexican crema, and minced garlic in a small bowl until smooth. Season with a pinch of salt.
In another small bowl, combine chili powder and cayenne pepper.
Once corn is charred, immediately brush or spread the creamy mixture all over each ear, coating completely.
Sprinkle generously with crumbled cotija cheese, pressing gently so it adheres to the creamy coating.
Dust with the chili powder mixture and garnish with chopped cilantro if using.
Serve immediately with lime wedges for squeezing over the corn just before eating.
Notes
Storage tip: The creamy sauce can be made 2 days ahead and refrigerated. Corn is best served immediately after charring, but can be reheated briefly if needed. For esquites (Mexican street corn salad), cut kernels off the cob after charring and serve in bowls with the same toppings.