To prepare the spaghetti squash, cut it in half lengthwise and scoop out the seeds with a spoon. Cut the squash in quarters and place them in the crock pot with water. Bring the water to boil, then reduce the heat to medium-low and simmer for 30 minutes. Remove the noodles from the pot and set them aside. In the same pot, heat the olive oil over medium heat until shimmering. Add the garlic and saute until fragrant, about 1 minute. Stir in 2 tablespoons of the tomato paste and 1 teaspoon of salt. Cook, stirring frequently, until the sauce thickens, 2 to 3 minutes more. Pour the meat sauce over the pasta noodles and toss to coat. Serve with Parmesan cheese and sour cream.