Preheat oven to 400 degrees. Line a sheet pan with parchement paper for easy clean-up or lightly grease the pan.
Place garlic cloves and cauliflower onto the sheet pan, drizzle with oil, and sprinkle with a large pinch of salt. Toss with your hands to combine then spread the cauliflower into an even layer. Roast until golden brown, 25 to 30 minutes.
While cauliflower is roasting, cook pasta. Drain and return to the pot. If using a lentil or bean based pasta, I find it best to rinse the pasta and pot with warm water after draining. Set aside until sauce is done.
Remove pan from oven and set aside. Once cool enough to handle, peel garlic cloves and discard the skin. Add garlic, roasted cauliflower, milk, and cream cheese to a blender. Blend until smooth and creamy. Add additional milk a little at a time if more liquid is needed to make a thick but pourable sauce. Taste then season with additional salt and pepper.
Pour sauce onto cooked pasta and stir to coat. Re-warm pasta over low heat, if necessary. Serve immediately or stir in grated cheese for some extra creaminess.
For Baked Mac and Cheese: Grease a baking dish (9-inch square, round, or individual ramekins all work well) with olive oil. Once pasta and sauce are combined, spoon the mixture into the baking dish. Sprinkle cheese on top, if using, then broil the top until browned and bubbly. Serve warm.