For the toast: In a large pan on medium heat, add the butter and garlic. Cook until the garlic is fragrant, about 4 minutes. Add the toast, soaking up a bit of the butter on one side, then flipping it to the other side to soak up the rest. Toast on one side until a peek beneath reveals a golden toasty color, then flip and toast the other side as well. Remove the toast to a plate.
For the sauce: In the same pan, add the butter, onions and bell pepper. Cook, stirring, until tender, about 2 minutes. Season with salt and pepper, then add the ketchup, brown sugar, chicken stock, beer, hot sauce, garlic powder, paprika, chile flakes and garlic. Cook, stirring, until the sauce thickens and the sugar is completely dissolved, 8 to 10 minutes.
Add the chicken to the sauce and stir to coat and re-heat. Spoon over the toast and serve.