The Times, "Dinner Tonight"
Melt 40g butter in a large frying pan, and cook the mushrooms with the zest from half the lemon, a squeeze of juice and thyme.
Grease a dish with 10g butter, and dust with parmesan. Pre-heat the oven to 220° (190° fan).
Make a white sauce with the flour, milk, and remaining 25g butter. Add salt, remaining lemon juice and 2 tbsp parmesan.
If using dried lasagne, soften the sheets in hot water for 2-3 mins.
Place 2 sheets lasagne in the bottom of the dish, top with half of the mushrooms half of the spinach, and a spoonful of sauce. Repeat. Finish with a layer of lasagne topped with the lion's share of the sauce. Finish with parmesan.
Place the lasagne in the oven and bake for 25-35 minutes until blistered and bubbling.