Blend all the creamy-layer ingredients until smooth.
Brown the beef in ½ tsp cooking fat or a quick spray. Drain the excess fat. Add the mushrooms, zucchini and onion and cook until soft and the moisture has cooked off. Add the tomato paste, then the passata and seasonings. Simmer uncovered 7-10 min until thick.
In a 9x9 dish, layer sauce, 2 lasagna sheets, sauce + creamy layer, 2 lasagna sheets, then the remaining creamy layer + sauce. Top with 30g Parmigiano.
Bake uncovered at 400°F/205°C for 40-50 min. Start checking at 35: it's done when the top is golden and the edges are bubbling. Rest 15-20 min before cutting into 4 giant slabs.
