Preheat your grill to medium-high heat and shuck the corn, removing all husks and silk.
Place the corn directly on the grill grates, turning occasionally, until the kernels are slightly blackened and charred around the edges, about 10-12 minutes.
Remove the corn from the grill and let it cool slightly, just until it’s comfortable to handle.
Mix the mayonnaise with the chili powder and melted butter (if using) in a bowl until well combined, creating a spicy, creamy coating.
Spread a generous layer of the spicy mayo mixture all over each ear of corn using a basting brush or spoon, ensuring it covers evenly and sticks to the charred kernels.
Sprinkle the crumbled Cotija cheese generously over the coated corn, pressing lightly to help it adhere.
Squeeze fresh lime juice over the corn, then sprinkle chopped cilantro on top for a burst of herbal freshness.
Serve the street corn immediately, with extra lime wedges on the side for an added zing, and enjoy the smoky, spicy, and creamy bites.