To make the roasted butternut squash recipe: Preheat your oven to 420°F (215°C). Cut squash lengthwise with a large sharp knife and scoop out seeds with a melon baller. Using a peeler, remove skin and white pith. Brush with oil and sprinkle with salt and pepper. Arrange butternut halves cut side down in a prepared baking pan side by side and roast until softened, about 20 minutes.
Meanwhile, in a small bowl, combine melted butter, oil, Cajun seasoning, minced garlic, and crushed black pepper. Set aside.
Remove squash from oven and transfer to a cutting board and allow to cool slightly. Using a sharp knife, cut slits 2 or 3mm apart in the squash, cutting almost but not all the way through. You can place the handles of two wooden spoons alongside the squash to act as a guard to prevent cutting through. Transfer to the baking pan and brush with the Cajun garlic butter sauce. Make sure to coat well and between the slices.
Roast butternut squash halves, basting with the cooking juice every 8-10 minutes, for 25-30 minutes. You can turn on the broiler for a few minutes to slightly grill the top at the end of cooking.
Serve the roasted butternut squash topped with fresh chopped parsley and a sprinkle of kosher salt. Enjoy!