In a large pot over medium heat, add the butter, followed by the chopped bacon. Cook until bacon renders its fat and begins to brown, about 3-4 minutes.
Add onion, carrots, Serrano pepper, garlic, and oregano; cook until vegetables begin to soften, stirring occasionally, about 5 minutes. Season with salt and pepper.
Add potatoes, water, and epazote. Raise the heat to medium high and bring to a low boil, then lower the heat back to medium and simmer for 8-10 minutes or until the potatoes are halfway cooked.
Add the zucchini and corn; simmer for additional 8-12 minutes or until the vegetables are completely tender. Transfer 2 cups of the chowder to a food processor or blender and puree until smooth. Stir the mixture back into the pot then add half and half and cook just until heated through. Adjust seasoning if needed. Garnish with queso fresco, chipotle chiles, and cilantro and serve immediately.