1/2 cup heavy whipping cream
2 Tbsp. freshly grated Parmesan
1/8 tsp. nutmeg
salt and coarsely ground pepper to taste
In a non-stick skillet, bring cream to a boil. Let boil until reduced by 1/3, about 5 minutes, stirring and scraping down the sides occasionally. Watch carefully to prevent boiling over. Turn heat to low and stir in nutmeg. Sprinkle parmesan over sauce and stir in gently. Add salt and pepper if desired. This sauce can be held over very low heat for about 15 minutes; if it thickens too much, add hot water (from pasta, if you're cooking it) about a teaspoon at a time until it thins again.