Tomato lasagne

This recipe came from one of those free Coles magazines (you know the ones you pick up on your way into the supermarket and it is half ads and half content).  It also prices the recipe on a per serve basis, probably as part of the Curtis Stone 'Feed your Family' promotion (details here).  This recipe does not fit into the feed your family for less than $10, but if you already have some of the ingredients then you probably can get the more perishable ingredients for less than $10.

Ingredients:
50 g butter
1/3 cup p flour
2 cups milk
400g can diced tomatoes, juice drained and reserved
Basil pesto
Fresh lasagne sheets
1 1/2 cups grated mozzarella
1 cup grated parmesan

Method:
Pre heat oven to 180 degrees, grease a 23cm lasagne dish.
Make a roux - melt the butter, add in flour, add combined milk and tomato juice.  Once lump free and combined simmer for 5 minutes (while stirring) and then leave it for 2 minutes on the heat to thicken, season.
Layer as follows:
1/4 of the roux
Lasagne sheet, spread with 1 tbs pesto
1/4 of the roux
1/2 the tomatoes
1/2 the mozzarella
1/4 of the parmesan

Lasagne sheet, spread with 1 tbs pesto
1/4 of the roux
1/2 the tomatoes
1/2 the mozzarella

1/4 of the parmesan
Lasagne sheet, spread with 1 tbs pesto
1/4 of the roux
Remaining parmesan

Bake for 40 minutes.

Top with an avacado, basil and fresh tomato salsa.