High protein veggie lasagna

Name: High protein veggie lasagna
Cuisine: European, Italian, Mediterranean
Ingredients: Tsp olive oil or frylight; 200g of the M&S frozen soffrito mix OR standard onion carrot and celery; 2 x 500g can puy lentils; 400ml chopped tomatoes; 350ml passata; (I'd probably do another 200ml chopped tomatoes if this will be mainly for prep!); 9ish lasagne sheets; 85g grated mixed cheddar and mozzarella; 2 bay leaves; 2 cloves garlic; Salt and pepper; 30g butter; Heaped tbsp plain flour; 200ml milk