To roast corn, preheat the broiler on your over. Brush corn with olive oil and a sprinkle of salt, then place on a baking sheet. Broil for 15-20 minutes, rotating until golden brown. Remove from oven and set aside. To roast peppers, see here. Once corn has cooled, cut it off the cob into a bowl. Cut peppers into chunks.
In a large stock pot, add olive oil and 2 tablespoons of butter. Once hot add in onion and garlic along with salt and pepper, stirring to coat. Cook on medium heat for 5 minutes until softened. Add in peppers and corn, stirring to combine well, then add in chicken stock and 1/3 cup half and half. Bring to a boil and continue to stir for 5 minutes, then turn off heat.
Carefully transfer hot soup to a high-powered blender (or use an immersion blender if desired) and puree until smooth. I left a bit of texture to mine, but you can puree until totally creamy. Place back in the pot and turn heat to medium-low. Stir in remaining butter and half and half, then let cook, stirring occasionally, for 10 more minutes. Serve immediately with green onions and tortilla chips!