Preheat your grill to medium-high heat, and lightly oil the grates with a paper towel dipped in oil to prevent sticking.
Place the shucked ears of corn directly on the grill grates, turning occasionally, until the kernels develop deep amber and blackened spots, about 8-10 minutes. You should hear a slight crackle as the kernels char and pop.
Remove the corn from the grill and set aside briefly to cool slightly, just enough to handle comfortably.
While the corn is still warm, brush each ear generously with the spicy mayo mixture using a basting brush, ensuring full coverage.
Sprinkle the crumbled Cotija cheese evenly over the coated corn, pressing lightly so it adheres to the mayo.
Sprinkle chili powder over the cheese-topped corn for heat and smoky flavor, then squeeze fresh lime juice all over to brighten the dish.
Drizzle the melted butter over each ear for richness, and sprinkle chopped cilantro on top for herbaceous freshness.
Serve the corn immediately while still warm, allowing the flavors to meld and the charred kernels to provide a satisfying crunch with every bite.
