To make these, whip a half pint of heavy cream with 1/4 cup sugar until stiff peaks form. Spread the cream in a 3/4-inch-thick layer onto a parchment paper–lined baking sheet. Freeze overnight. Cut out shapes using cookie cutters, then decorate with sprinkles or sanding sugar. Use immediately, or freeze in a plastic container between sheets of parchment for up to a week.