Melt the butter in a medium saucepan, add the onions and cook over medium heat until they are soft. Add the peppers and stir to coat with butter. Cook for a minute, add the flour, stir to coat the veggies, and cook for another minute. Add the beer and the half & half, whisk gently, so there are no lumps but not so hard the veggies disintegrate. Stirring constantly, heat the liquid until it thickens and has a smooth texture, about 4-8 minutes. Add both kinds of cheese and whisk until they are melted. Taste and add salt if needed. Garnish with more fresh peppers or cilantro. Serve with tortilla chips and pretzels.