1) Char the poblano chillies directly over the gas flame on the stove or under the broiler until blackened on all sides. Enclose in a plastic bag and let steam for about ten minutes.
2) Add the oil to a heavy large frying-pan over medium heat. When the oil is hot, add the onion and saute until translucent, about five minutes. Add the corn and cook for an additional three minutes. Set aside.
3) Peel and seed the chillies. Cut the chillies into 1/2 - 1cm strips (rajas) and add the strips to the onion and corn mixture and saute until the corn is tender, about five minutes. Add the double cream and Mexican crema and cook until bubbling, about for eight minutes. Add the cheese and stir until melted and smooth. Season the rajas with salt and pepper, to taste. Transfer to a serving dish and serve.
Notes: The poblano chilli is a fresh chilli that ranges from mild to hot. It is a deep, dark green color and is large and wide with shiny skin. Ripened on the plant and dried it is known as "chilli ancho" or "pasilla." They can also be found at most supermarkets or Latin specialty markets. Just keep your eye out, as some stores sell them fresh under the name "pasilla."
A great filling for tacos or topping for grilled arrachera. You can use virtually any chile but a mild poblano adds the perfect amount of spice to any dish.