Heat oil in a large saucepan over medium heat. Add onion and garlic and cook for 2 mins or until soft.
Add beef mince and cook for 10 mins or until brown. Add 500 ml Campbell’s Real Stock - Beef (keep remaining stock for sauce), oregano, diced tomatoes and tomato paste. Cook uncovered for
Meanwhile in another small to medium sized saucepan, melt the butter over medium heat, remove from heat and whisk in the flour. Return to heat and slowly add the remaining 500 ml of stock, a little at a time, stirring continually to avoid lumps forming. Bring to the boil, add mozzarella and stir until thickened. Remove from heat.
Spread 1 ½ cups of meat sauce over the base of a 2 ½ litre baking dish, top with stock sauce, then lasagne sheets, breaking to fit if necessary. Then repeat; meat sauce, stock sauce, lasagne sheets, continue this process then top with grated cheddar and bake for 30 - 35 minutes.