Preheat grill for indirect grilling over medium heat.
Peel back the corn husks, leaving them attached, and remove as many of the silks as you can. Spread 1 tablespoon of butter on each ear of corn, then replace the husks to cover the ears of corn.
Grill corn 10 minutes over indirect heat, then remove from grill and let sit until cool enough to handle. (Keep grill heated for bratwurts.)
Meanwhile, in a small bowl, stir together garlic, mayonnaise, sour cream, lime juice, chili powder, and paprika until well combined.
Carefully unwrap corn and cut corn kernels from cobs.
Mix together corn and mayo mixture in a medium bowl. Transfer to a prepared baking dish, and bake at 350° for 15-20 minutes or until heated through and the flavors have melded.
Meanwhile, grill brats for 15 minutes over indirect heat, turning occasionally. Transfer brats to direct heat and increase temperature to medium-high. Cook an additional 5 minutes or until browned with an internal temperature of 160 degrees F. Remove from grill and turn off heat.
Place brats in buns; top with baked street corn mixture, green onions, cotija or feta cheese, fresh cilantro leaves, and extra chili seasoning for garnish. Serve.