In a medium bowl, beat together the butter, lime juice, ½ cup of feta, chili powder, cayenne pepper, salt, and pepper until combined. Spoon onto a sheet of wax paper, and roll into a log. Freeze butter until chilled, at least 30 minutes.

Preheat your grill to medium-high. Brush the corn cobs with olive oil. Grill each side 6-7 minutes, turning occasionally until the corn is tender, around 15 minutes. Transfer the ears to a platter.

Remove chilled butter and cut into 1 inch pieces. Add remaining feta to corn as a garnish. Serve both over corn.