Preheat oven to 500 degrees F (260 degrees C). Line a baking sheet with aluminum foil and add poblano peppers. Brush peppers with 1 tablespoon vegetable oil. Roast poblano peppers in the preheated oven for 20 minutes; flip and continue roasting until skin is charred and flesh is soft, about 20 minutes more. Place roasted peppers in a bowl and cover with plastic wrap; let steam for 10 to 15 minutes. Carefully remove plastic wrap and peel the skins from the peppers and remove seeds and stems. Cut peppers into strips. Bring a pot of water to a boil; cook corn kernels until soft, about 10 minutes. Drain. Heat 1 tablespoon vegetable oil and butter in a saucepan over medium heat; cook and stir onion until soft, 5 to 10 minutes. Add poblano pepper strips and corn; season with chicken bouillon granules and cook for 3 minutes. Reduce heat to medium-low and stir in cream and manchego cheese; simmer until cheese melts, about 5 minutes.