Scoop out and discard seeds from 1,8kg (2 small or 1 large) butternut, halved lengthwise. Prick outsides all over with a sharp knife; season insides with ¼ tsp each salt and pepper. Microwave, cut-sides down, on a large microwavesafe plate on high for 10 minutes or until tender. Meanwhile, in a small pot, heat 1 cup evaporated milk and 3 tbsp butter to simmering on a medium-low heat; simmer for 5 minutes or until reduced slightly, then whisk in 1 cup finely grated Parmesan cheese. With a fork, scrape flesh of each butternut half, leaving a 1cm border on the sides; divide sauce among the halves and top each with 2 tbsp grated mozzarella cheese. Grill for 1 to 2 minutes or until bubbly and browned in spots. Optional: serve with a green salad.