Place 2 cups corn kernels in a large nonstick or cast iron skillet and cook over medium-high heat, stirring occasionally, until browned in spots, about 5 to 6 minutes. Transfer to a large plate and let cool for about 10 minutes.

Meanwhile, stir together 2 ounces crumbled Cotija cheese, 3 tablespoons Mexican crema, 3 tablespoons lime juice, 2 tablespoons mayonnaise, 1/2 teaspoon cayenne pepper, and 1/4 teaspoon garlic powder in a large bowl.

Stir in the cooled corn, 1 pound English cucumber cut into half-moon slices, 1 thinly sliced medium shallot, and 1/4 cup coarsely chopped fresh cilantro if using. Taste and season with kosher salt and black pepper as needed. Garnish with more crumbled Cotija cheese if desired.