To thicken whipping cream for a pasta sauce, you can use one or a combination of the following techniques:
Reduce the cream: Simmer the whipping cream gently over low heat until it reduces and thickens to the desired consistency. Keep an eye on it and stir occasionally to prevent scorching. The reduction process evaporates some of the liquid, resulting in a thicker sauce.
Roux: Prepare a roux by melting butter in a separate saucepan and gradually whisking in an equal amount of all-purpose flour until a paste-like consistency forms. Cook the roux for a minute or two to eliminate the raw flour taste. Then, gradually whisk in the whipping cream, allowing the mixture to thicken as it cooks.
Cornstarch slurry: In a small bowl, mix cornstarch with a small amount of cold water to create a slurry. Add the slurry to the whipping cream while whisking continuously. Heat the cream gently until it thickens, being careful not to overcook it. Cornstarch is a common thickening agent that helps sauces achieve a thicker consistency.
Cream cheese or grated cheese: If you're open to adding extra flavor to your pasta sauce, you can incorporate cream cheese or grated cheese into the whipping cream. As the cheese melts, it will contribute to the thickening of the sauce while adding a creamy and savory element.
Remember to adjust the seasoning of your sauce as necessary after thickening it, as some methods may dilute the flavors slightly. Additionally, it's always a good idea to start with a smaller amount of thickening agent or reduction and gradually add more as needed, as you can continue to thicken the sauce if necessary but reversing the process can be challenging.