Preparation

• Chill the bowl and mixer beaters (this is very important if your kitchen is warm). Mix the sugar and cream of tartar together. Whip the cream in a medium bowl with an electric mixer on high just until it begins to thicken. With the mixer running, add the sugar mixture, then the vanilla, and continue beating until the cream stands up in peaks that are stiff but still soft enough to flow. Don’t overbeat at this stage or the cream will curdle. For best results, use immediately or refrigerate and use within 30 minutes.
• Fit the right size decorating tip onto a pastry bag. Use a coupler to attach them, so you can change the tips easily without cleaning out the bag each  time. A few decorating tips are too large for a coupler, so use these larger tips inside a bag with a small hole and fit the tip snugly inside before adding the whipped cream.
• Put the frosted cake in the freezer for 30 minutes to set the decorations. Transfer to the refrigerator until time to serve.
• Note: For whipped cream rosettes with deep, more decorative ridges, use closed-star tips: #845, #846, or #847 for large rosettes and stars; #30, #35, or #844 for medium-size ones.For decorations with a “softer” look and fewer details, choose open-star tips: #825, #826, or #827 for large rosettes and stars; #1M, #4B, or #822 for  medium-size ones.

For 6 cups Decorator’s Never-Fail Whipped Cream (enough to fill, frost, and decorate a 3-layer cake):
Prepare as directed using 1⁄3 cup confectioners’ sugar, 1⁄2 tsp. cream of tartar, 1-1⁄2 pints (3 cups) icy-cold heavy or whipping cream, and  1 Tbs. pure vanilla extract.

For 8 cups Decorator’s Never-Fail Whipped Cream (enough to fill, frost, and decorate a 4-layer cake):
Prepare as directed using 1⁄2 cup confectioners’ sugar, 1⁄2 tsp. cream of tartar, 1 quart (4 cups) icy-cold heavy or whipping cream, and 2 Tbs. pure vanilla extract.