Pre-heat the oven to 400 degrees. Place the shrimp, onions, and peppers on a large sheet pan. Melt the butter and mix together with the liquid smoke. Pour over veggie and seafood mixture. In a separate bowl, mix together the sweetener and spices. Sprinkle evenly over the veggies and seafood, place pan in the oven and bake for 20 minutes. Enjoy!