In a large bowl, combine the first 6 ingredients. In another bowl, whisk egg and buttermilk., Place butter in an 8-in. cast-iron or other ovenproof skillet; heat skillet in a 425° oven until butter is melted, 3-5 minutes. Meanwhile, stir egg mixture into dry ingredients just until moistened. Fold in peppers and bacon., Carefully swirl the butter in the skillet to coat the sides and bottom of pan; add batter. Bake at 425° until a toothpick inserted in the center comes out clean, 18-22 minutes. Cut into wedges; serve warm.