Melt the butter (or heat the olive oil) in a small skillet over medium heat. Add the garlic and cook for about 1 minute until fragrant; do not brown.
In a blender, combine the cottage cheese, milk, half the Parmesan, the sautéed garlic, salt, pepper, and nutmeg. Blend on high for 60-90 seconds until completely smooth.
Pour the blended mixture into a saucepan over medium-low heat. Stir frequently and warm gently for 3-4 minutes, without letting it boil.
Stir in the remaining Parmesan until melted and the sauce is smooth.
If the sauce is too thick, loosen with a splash of reserved pasta water or extra milk.
Toss the warm sauce directly with hot, drained pasta until coated. Garnish with extra Parmesan, black pepper, and parsley.