Roast poblano either by holding over a gas flame (with tongs!) until blackened or roasting in the oven. Place in a small bag and seal for 10 minutes. Remove skin, stem, seeds and dice pepper.
Using a sharp knife, cut the kernels from the cob and set aside. Dice onions and set aside.
In a skillet over medium high heat, add oil and onions and cook 3-4 minutes or until onions are beginning to cook through. Add poblanos and cook for 1-2 minutes. Add corn kernels and cook for 2-3 minutes, then add butter, salt, peppers and garlic.
Add cream and cook while stirring for 2 minutes, or until cream is thickened. Sprinkle in wondra flour, if desired, stir and serve.