Just make a vegan béchamel and then build your lasagne by filling a deep oven dish with alternate layers, starting with a layer of bolognese in the base of the dish. Then a layer of sheet pasta, followed by a layer of béchamel, then another layer of sheet pasta. Repeat this process until the dish is full, making sure that the top layer is béchamel. bake the constructed lasagne in an oven at 180c for 25-30 minutes.