Step 1

Heat your oven to 220C/430F fan and line an oven tray with baking paper. Chop the end (with the stem) off your squash, then cut it straight down the middle, so you’re left with two long pieces of squash. Use a spoon to scoop out the seeds, then place them in a bowl and set aside. Slice the tops of your heads of garlic off, then drizzle the exposed sides of the squash with 1 tablespoon of olive oil and 1 teaspoon of salt. Place the garlic in the cavity where the seeds were, then place the squash, cut side down, on the tray. Roast for about 45 minutes, until deeply golden and soft all the way through when you pierce it with a knife.

Step 2

While the squash is roasting, soak the discarded seeds in water and remove as much of the squash flesh as you can. Pat them dry with a piece of kitchen towel, then spread them out on another oven tray and scatter with 1 teaspoon of flaky sea salt and 1 teaspoon of paprika. Toss to coat the seeds, then push them to one side of the tray, and lay out the prosciutto slices on the other side. Transfer to the oven with the squash, for 5 or 6 minutes, until the seeds are lovely and toasted and the prosciutto is super crispy. Set aside.

Step 3

Once the squash is super soft, remove it from the oven. Pour the pasta straight into a large, high-sided pan or skillet, then scoop the squash out of its skin with a spoon, straight into the pan. Squeeze the garlic out of its skin into the pan too, along with 2 teaspoons of fish sauce, 2 teaspoons of salt, 1 teaspoon of Dijon mustard, 1 cup of milk and 2 cups of vegetable stock. Stir to mix everything through the pasta, then set over medium heat.

Step 4

The pasta will take about 12 minutes to cook (use your packet to guide you) until it’s al dente (cooked, but still with a little bite to it). Stir the pasta occasionally, so that nothing sticks to the bottom of your pan. You may need to add a little more milk, stock (or water), depending on the pasta you use and how saucy you like your mac and cheese.

Step 5

Once the pasta is just al dente, add both cheeses and a good grind of black pepper, then stir them through the pasta as they melt into the sauce. Taste, then season with a little more salt if needed. Remove the pan from the heat, then scatter over the toasted seeds, crumble up the crispy prosciutto and scatter that on top too. Divide between plates and serve while hot and oozy. PRO TIP: If you like, you can pop the cooked mac and cheese under the broiler (grill) for 5 minutes at the highest heat, just to crisp up the top.