Preheat the oven to 180OC. Grease the lasagna dish.

Melt butter in a heavy-based saucepan over medium heat. Add flour. Cook, stirring for 1-minute. Or until mixture is bubbling. Remove from heat. Slowly add milk until mixture is smooth. Return to heat. Cook, stirring for 10 minutes or until mixture comes to boil.

Spreads a spoon of bolognaise sauce on to the base of baking dish. Cover with lasagna sheets. Spoon over half remaining bolognaise sauce. Top with 1/3 of the white sauce. Spread evenly the bolognaise and ricotta cheese. Repeat. Top with final layer of lasagna sheets. Spoon the remaining white sauce over the lasagna sheets. Spread evenly. Sprinkle with shredded mozzarella cheese.

Bake the lasagna with cover for 40 minutes. Take off the lid. Re-bake for 15 minutes or until the lasagna surface golden brown and the lasagna sheets are tender. Stand for 10 minutes before serving.