Half fill a large pot with water and top with a steamer basket. Add the butternut squash cubes to the steamer basket, place the lid on and bring to a boil. Cook until the butternut squash is tender. Turn off the heat and set aside.

While the pasta is cooking, bring a large shallow casserole pan to a medium heat. Drizzle with olive oil and then snip the end of each sausage and push the sausage meat out of its casing and into the pan. Use a spatula to break the sausage meat up as it cooks into small chunks. Once all the sausage meat is cooked, transfer to a plate.

Add the butter to the pan. Once melted, add the sliced leeks and sauté until tender. Add the sun-dried tomatoes and minced garlic and sauté until fragrant.

Add the flour to the pan and stir to combine with the melted butter, leek, garlic and sun-dried tomatoes. Pour in a third of the milk and whisk straight away. Add another third and whisk and then the final third and whisk until there are no lumps. As the sauce starts to thicken, add the chicken stock and continue stirring until smooth and creamy with no lumps. The mixture should be thick enough to coat the back of a wooden spoon.

Add the dried thyme, salt and pepper to the sauce and stir to combine. Add the kale and stir through to wilt. Once the kale is wilted, turn off the heat.

Add the pasta, cooked sausage and steamed butternut squash to the pan and toss through the sauce until well combined.

Spread out into an even layer and top with grated mozzarella and cheddar cheese. Place the pan into the oven and bake for 15 minutes or until the top is turning golden brown. Serve hot.