Dry the corn and spread it out on a heavy baking sheet.
Broil for 5 minutes or so, stirring around often, to caramelize the kernels.
In a large stockpot melt the butter.
Add the onion and sauté until it begins to soften.
Add the garlic - sauté for about 3 minutes.
Add the chicken stock, heavy cream, chipotle, chili powder, and cumin to the stock pot.
Bring to a simmer and add the corn.
Simmer for about 10 minutes, stirring often.
Remove 2 cups of the corn to a blender.
Add 2 1/2 cups of the hot broth.
Blend until smooth.
Return to the pot.
Bring back up to a simmer.
Stir together the crema, mayo, 2 tablespoons cilantro, and lime.
Add to the stockpot and stir until smooth.
Taste and adjust seasonings to your preference.
Ladle into bowls and top with the Cojita cheese and remaining chopped cilantro.
To make in a slow cooker follow through instruction 8 but leaving the cream out. Heat on low for up to 8 hours. Just before serving add the cream and blend the corn and broth in the blender - then continue with the recipe.