In an 8-inch skillet, combine 3/4 cup heavy cream, 2 tablespoons butter and 1/2 teaspoon salt over medium-high heat. Bring to a simmer and cook, stirring, until thick enough to coat a spoon, about 4 minutes. Stir in 2 tablespoons chopped flat-leaf parsley and remove from the heat. Add 1/3 cup grated parmigiano-reggiano cheese when tossing with pasta. Makes 2/3 cup.