Root veg & ricotta lasagne

Name: Root veg & ricotta lasagne
Prep time: 15 min
Cook time: 1 h 35 min
Total time: 1 h 50 min
Cuisine: Italian
Ingredients: 3 large carrots, grated; 3 large parsnips, grated; 1 sweet potato, grated; 1 tbsp thyme leaf, roughly chopped; 500g carton passatawith onion & garlic; 2 tbsp tomato purée; 250g ricotta; 200g tub crème fraîche; 2 medium eggs, beaten; 80g pack grated parmesan(or vegetarian alternative); oil, for greasing; 6 dried lasagnesheets