Roasting or Charring the Poblano Peppers:

1. To Char: Char the poblano peppers, one by one, over the gas flame until blackened and blistered on all sides. Enclose the charred peppers in a bag, and allow to steam for 8 to 10 minutes.
2. Broiling: Line a baking sheet pan with aluminum foil (optional). Place the poblano peppers on the baking sheet.
3. Set an oven rack about 6-inches from the heat source and turn on the broiler to high. Place under the broiler and let the peppers broil, turning them as needed, until completely charred and blistered. Transfer the peppers to a bag to steam (alternatively, cover the baking pan with aluminum foil and allow peppers to steam for 8 to 10 minutes).
4. Transfer the peppers to a cutting board and peel off as much of the skin as possible. To make peeling easier, I rub off the skin with a piece of paper towel. It usually comes off quite easily.
5. Remove and discard the stems and seeds, and cut the peppers into 1/4 to 1/2 inch thick slices (rajas)
6. Heat oil and butter in a large skillet over medium heat. Sauté the onions until they soften and become translucent, about 5 minutes. Add the garlic and cook, stirring frequently, for about 30 seconds or until fragrant.
7. Stir in the corn and cook for about 2 minutes, stirring as needed. Add the poblano peppers or rajas and cook, stirring frequently until the corn becomes tender, about 2 minutes (cook a bit longer is making this recipe with fresh corn).
8. Add the half and half and Mexican crema (or creme fraiche) and stir together to combine. Cook until bubbling, about 5 minutes. Remove from the heat, add the cheese stirring until completely melted and smooth. Serve hot with warm flour tortillas or with tortilla chips.