Chipotle chiles and pepper jack cheese bring the perfect note of heat to this creamy casserole. Good quality frozen corn makes a big difference here, as some brands tend to be starchy with little flavor.
Preheat oven to 350 degrees. Butter a 2-quart baking dish and set aside.
In a medium skillet, melt 2 tablespoons butter over medium-high heat. Add onion and pepper and cook, stirring often, until golden brown and caramelized, about 8 minutes. Add garlic and cook until fragrant, 1 minute. Add chipotle and season with salt and pepper. Transfer to a large bowl to cool to room temperature.
Puree 3 cups corn in a food processor or blender until very smooth. Transfer to bowl with onion mixture. Stir in 1 1/2 teaspoons salt, cornmeal, remaining cup corn, and cheese. In a separate bowl, whisk together 6 tablespoons melted butter, cream and eggs just until combined. Fold into corn mixture. Pour batter into prepared dish and bake on a rimmed baking sheet until puffed and golden and the center jiggles slightly, 45 to 50 minutes. Let cool 15 minutes. Serve with salsa, cilantro and sour cream.