Start the Traeger on Smoke for 4-5 minutes with the lid open to establish the fire.
When the Traeger starts smoking, place the sausage on the grill and smoke for 30 minutes (optional). Remove the sausage and turn the temperature setting to 375 degrees F. Preheat, lid closed, for 10-15 minutes.
Return the sausage to the grill, along with the sliced onions and head of garlic. Grill the sausage and onions for about 5-7 minutes per side. Leave the garlic on the grill for about 25 minutes total.
In 10-inch skillet, add tomatoes, tomato sauce, 2 tablespoons of the parsley, the basil, and sugar. Heat to boiling, stirring occasionally. Reduce heat to low; simmer uncovered about 45 minutes or until slightly thickened. Slice the cooked sausage and finely dice the grilled onions. Add them to the sauce. When the garlic is browned and tender, squeeze it from the peel and mince finely. Add directly to the sauce.
In medium bowl, mix ricotta cheese or cottage cheese, 1/4 cup Parmesan cheese, remaining 1 tablespoon parsley and the oregano. Spread 1 cup of the sauce mixture in ungreased 13x9-inch (3-quart) glass baking dish. Top with 4 noodles.
Spread 1 cup of the cheese mixture over noodles; spread with 1 cup of the sauce mixture. Sprinkle with 2/3 cup of the mozzarella cheese.
Repeat with 4 noodles, the remaining cheese mixture, 1 cup of the sauce mixture and 2/3 cup of the mozzarella cheese. Top with remaining noodles and sauce mixture. Sprinkle with remaining mozzarella cheese and 1/4 cup Parmesan cheese.
Cover with aluminum foil and bake at 375 degrees for 30 minutes.
Uncover; bake about 15 minutes longer or until hot and bubbly. Let stand 15 minutes before cutting.