Cook the Corn Mixture:
In a large pot, heat 4 tablespoons of vegetable oil over medium heat. Add the cooked frozen corn, diced onion, salt, and pepper. Cook for about 10 minutes, stirring occasionally, until the corn is browned and slightly charred. Scoop out 1 cup of the corn mixture and set it aside for garnishing.
Add Garlic and Broth:
Add the grated garlic to the pot and stir for about 1 minute. Pour in the chicken broth, making sure to scrape the browned bits from the bottom of the pot (this adds tons of flavor). Let the mixture simmer for 6 minutes.
Blend the Chowder Base:
Carefully transfer the mixture to a blender, leaving the center cap loose to allow steam to escape. Blend until smooth, then return the blended mixture to the pot over low heat.
Add Cheese and Spices:
Stir in the Cotija cheese, shredded pepper jack cheese, diced red pepper, half & half, reserved ½ cup of corn, chopped cilantro, lime juice, garlic powder, and chili powder. Taste the chowder and adjust seasoning or add more chili powder for heat if desired. Simmer for another 10 minutes to let the flavors meld.
Serve and Garnish:
Ladle the chowder into bowls and top with additional crumbled Cotija cheese, chopped cilantro, the reserved charred corn, a sprinkle of chili powder, and a squeeze of lime juice. Serve hot and enjoy!