Pre-heat the oven to 160°C. Bring a large saucepan of water to the boil.
Finely crush the garlic into a saucepan sprayed with low calorie cooking spray and cook on a low heat for about 5 minutes, stirring frequently and being careful not to burn it.
Keeping the heat low, add the passata, chopped tomatoes, tomato puree and herbs. Mix well, add a pinch of sweetener and turn the heat up until it starts to bubble or "blip". Leave to reduce for 15 minutes on a moderate heat, stirring occasionally.
Meanwhile, finely chop the pepper and slice the mushrooms and tomato. Grate the cheddar cheese and tear the mozzarella into pieces.
Spray a 24cm spring form tin with low calorie cooking spray. Place the rigatoni pasta tubes upright into the tin - it's best to start at one side of the tin and work across as this keeps them more upright.
Once the tin is full, squeeze as many tubes of pasta into the gaps as possible - you'll be surprised how many you can fit in!
Once the tin is full of the rigatoni, pour over the tomato sauce and spread over the top of the pasta. Top with the grated cheddar first, followed by the peppers, mushrooms, mozzarella and finally the tomato slices.
Bake in the oven for around 25 minutes until the cheese is golden. Remove from the oven and run a knife around the edge before unclipping the tin to remove the outer ring. Cut into wedges and serve with a salad!