Soak corn in water for at least 15 minutes.

Prepare a grill for medium-high heat and preheat a Carbon Steel Griddle on grill for at least 5 minutes.

Remove stems and seeds from chiles and toast on Griddle until blackened in spots, about 5 minutes per side.

Transfer to a bowl of hot water and let soak until softened, 15–30 minutes.

Remove corn from water, shake off excess water, and pat dry. Peel back corn husks, remove silk, and tie together at bottom using a strip of husk. Set aside.

Drain chiles, reserving 2 Tbsp. soaking liquid. Transfer chiles, crema, garlic, and lime juice to a high-speed blender and blend until texture is creamy and color is bright burnt orange. If crema is too thick, add reserved soaking liquid 1 Tbsp. at a time until desired consistency is achieved.

Transfer guajillo crema to a medium bowl. Top with pumpkin seeds and sprinkle with pepper flakes. Set aside.

Brush kernels with butter and place on Griddle. Turn corn until dark char marks appear, about 2 minutes per side.

Spread corn with guajillo crema and top with Cotija, cilantro, and pepper flakes.