On the hob melt the 50g butter, fry onions, bacon and garlic until soft. Add chicken and cook gently until just turning brown. Stir in 1 tablespoon flour and cook for one minute. Add stock cube, tinned tomatoes and basil. Cover with a lid and simmer for 10 to 15 minutes.
To make sauce: Melt the 25g butter, add the 25g flour and cook over low heat for one minute. Add milk a little at a time, stirring continuously beat until smooth. Add cheese and stir in.
To make lasagne: Use a large ovenproof dish. Pour in half of the chicken mixture then layer with four lasagne sheets and then layer again with remaining chicken and lasagne on top.
Pour the cheese sauce on top.