In a 1-quart saucepan over medium heat, stir together the heavy cream and lemon juice. Add the butter and stir until melted. Reduce heat to medium-low and whisk for about 8 minutes, until the mixture thickens slightly.
Stir in the Parmesan and nutmeg. Continue stirring for about 3 minutes, until the cheese melts and the sauce thickens.
Remove from heat. Toss with cooked pasta or use over chicken or shrimp.The sauce thickens as it cools. Taste and add ⅛ teaspoon of salt if needed.
