Preheat oven to 350 degrees. Spray a baking sheet with baking spray or line with parchment paper.
Heat a large skillet over medium high heat. Add sausage and crumble as it browns. After about 2 minutes, add onions, peppers and garlic. Cook until sausage is just cooked through and vegetables are softened. Remove from heat and drain any grease off the sausage. Lightly flour a smooth counter surface and roll out dough into a large rectangle, about 12x18 inches. Evenly sprinkle pizza seasoning and crushed red pepper flakes over dough. Spoon sausage mixture onto bottom third to half of the long edge of the dough, leaving an edge of about one inch open at the outside. Next add cheeses directly next to the sausage mixture on the 2nd third of the dough, a little overlap is fine. The final third should be open.
Begin rolling from sausage side, rolling the dough gently into a long tube. Pinch the seams to seal the dough and place the dough seam side down on prepared pan. Fold the ends under slightly, pinching to seal the ends. Bake about 25 minutes and remove from oven. Add garlic powder to melted butter and brush over the top of the bread dough and return to the oven for about five more minutes until golden brown. Cool at least 5-10 minutes before slicing into 1/2 inch thick slices. Serve with warmed pizza sauce.