Preheat oven to 350 degrees F (175 degrees C). Spray a glass 9x13 inch baking dish with cooking spray. Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes, or until al dente; drain.

Meanwhile, heat canola oil in a large skillet over medium-high heat until it begins to smoke. Add venison and cook, stirring to break apart, until browned and cooked. Drain off any excess oil, then stir in onion and green pepper. Cook for a few minutes until the onion softens, then stir in tomato paste, diced tomatoes, and water until combined. Season with salt, garlic powder, and pepper. Stir together drained macaroni and tomato sauce and pour into prepared baking dish.

Bake in preheated oven for 45 minutes, then sprinkle evenly with shredded Cheddar cheese, and continue baking until the cheese is bubbly and browned, about 15 minutes.