There is no contest between convenience foods and home prepared dishes, especially as you know exactly what is going into the food you cook at home. I buy my meat from a family butcher where the provenance of the meat can be demonstrated.
If you have prepared the meat sauce in advance, use the all-in-one method for making the bechamel, and buy freshly made pasta, this recipe is far less time consuming. Of course domestic goddesses could also make their own lasagne too, but I'm only Sandra Lawson, not Nigella.
Preparation Time: About 20 minutes if the meat sauce has already been prepared, but several hours if you need to make the ragų from scratch
Cooking Time: 15 minutes at 200°C
Makes: 4 servings
If you haven't already made the meat sauce you will need to get a head start. If it is already made, it will need to be allowed to thaw, but whatever stage of preparation you are at, you will need to reheat it gently.
Use the all in one method to make the bechamel sauce. Add the butter, plain flour and cold milk to a pan and heat gradually, whisking as you go. Once the butter has melted and the flour is incorporated, turn up the heat to medium and stir with a wooden spoon until the sauce is thick enough to coat the back of the spoon.
Grease the lasagne dish with butter and line the pan with a layer of lasagne pieces, cutting larger ones to fit. They can overlap, but not by more than 6mm.
Add a layer of meat sauce and bechamel, followed by a sprinkling of parmesan cheese.
Repeat the layers several times, ending with one of meat ragų.
Top with parmesan cheese and bake for about 15 minutes until a crust forms on top.
Remove from the oven and allow to rest for about 10 minutes before serving.