Preheat the oven to 180°C. Cook the pumpkin and butternut in a saucepan of boiling salted water for 7-10 minutes until tender and then drain. Purée in a blender with the vegetable stock and ground cinnamon. Season to taste.
To make the cheese sauce, melt the butter in a saucepan and whisk in the flour to make a paste. Gently cook the paste for a minute over low heat before whisking in the milk a little at a time to combine. Cook the white sauce over a medium heat for 10-15 minutes before removing from the heat and stirring in the cheese.
(You can use store-bought cheese sauce, but heat it up before assembling your lasagne so that everything is at the same temperature.)
To assemble the lasagne, cover the bottom of a baking dish with a layer of pumpkin purée, top with cheese sauce and then lasagne sheets. Repeat until the dish is full. Finish with a layer of cheese sauce, sprinkle over some more cheese, crumble over the feta and top with a few sprigs of thyme. Bake for 30 minutes until bubbling and golden.
Recipe by Hannah Lewry, courtesy City Press iMagazine.