1) Warm 45ml of olive oil in a large, heavy frying pan over medium-high heat. Add the butternut squash, garlic, one tsp salt, and 1/4 teaspoon freshly ground black pepper. Saute until the squash is golden and tender, five to seven minutes.
2) Add the vegetable stock, bring to a simmer, cover and cook until the squash is very soft, another five to seven minutes.
3) Transfer the squash mixture to a blender or food processor and puree.
4) Bring a large pot of salted water to a boil over high heat. Add the pasta and cook until tender but still firm to the bite, stirring occasionally, about 8 to 10 minutes. Drain pasta.
5) Meanwhile, warm the remaining 45ml of olive oil in a large, heavy frying pan over medium-high heat. Sprinkle the prawns with the remaining one teaspoon of salt and remaining 1/2 teaspoon of freshly ground black pepper. Add the prawns to the pan and cook until just pink, about three minutes.
6) In a large pot over low heat combine the cooked pasta, pureed squash mixture, and 185ml milk. Stir to combine. Add the remaining 65ml milk if the sauce needs to be moistened. Add the cooked prawns, basil, and cheese.
7) Stir until warm and serve.