Preheat oven to 400 degrees. Rub a baking dish or oven-proof skillet with butter.
In a large skillet over medium-high heat, melt butter until foaming. Add corn, bell peppers, onion, jalapeño, and 1 teaspoon salt and cook until softened, about 7 to 10 minutes. Stir in garlic until fragrant, about 30 seconds. Remove from heat and cool 5 minutes.
Meanwhile, in a large bowl combine cream cheese, mayonnaise, and sour cream until completely smooth. Stir in half the mozzarella cheese, green chiles, scallions, and chili powder. Carefully fold in corn mixture and season to taste with salt and pepper.
Spread into prepared baking dish and top with remaining 4 ounces mozzarella. Bake uncovered until hot and bubbly, 20 to 25 minutes. Remove from oven and garnish with scallions and cilantro if desired. Serve hot with tortilla chips.
Frozen corn: If it's sweet corn season, replace the frozen corn with 4 ears of fresh corn. To prepare the fresh corn, bring a large pot of water and 1 tablespoon salt to a boil over high heat. Add 4 ears of corn and boil for 3 to 5 minutes. Submerge ears in a large bowl of ice water. When the corn is cool enough to handle, cut it off the cob and transfer to a large bowl. Or substitute 2 14.5-ounce cans of corn, if desired.
Shredded mozzarella cheese: Some pre-shredded mozzarella may contain an ingredient to prevent the shreds from sticking together. For this recipe, I recommend grating the mozzarella cheese yourself from a block of cheese.
Canned green chiles: Or substitute chopped roasted red peppers if you enjoy their smoky flavor more.
Cilantro: Omit or swap in parsley if you don’t dig cilantro.
Yield: This Hot Corn Dip recipe makes 10 appetizer-sized servings.
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Make ahead: This dip can be assembled and stored covered (and unbaked) in the refrigerator 3 days in advance. Hold off on adding the shredded mozzarella until baking time.