Have your cookies baked and cooled completely. You can use this recipe, or your favorite recipe for cookies.

With a handheld or stand mixer fitted with a paddle attachment, beat the butter on medium speed until creamy, about 2 minutes. Add the confectioners’ sugar, heavy cream, vanilla extract, and salt. Beat on low speed for 30 seconds, then increase to medium-high speed and beat for 2 full minutes. Taste. To thicken the buttercream, beat in more confectioners’ sugar. To thin out the buttercream, beat in more heavy cream. To help offset more sweetness, beat in an extra pinch of salt.

Color the icing: If you’d like to tint the frosting, divide it into separate bowls for each color, or tint the entire batch one color. A little gel food coloring goes a long way, so use a toothpick to dot the gel into the icing. Stir it in, and then add more to deepen the color if desired.

Use piping tips or knife/icing spatula: You can use a knife or icing spatula to frost the cookies. Or, if using piping tips, fit a piping/pastry bag with a piping tip (and use a coupler if you plan to switch frosting colors and/or piping tips). Spoon the buttercream into the bag, making sure to leave a few inches of space at the top of the bag. Twist the end of the bag or use a clip to seal it shut. You can pipe zig-zags, swirls, lines, dots, or whatever your heart desires! See video tutorial below for some inspiration.

Cover and store decorated cookies at room temperature for 1 day, or in the refrigerator for up to 5 days. Frosting “soft-sets” on the cookies after a few hours, meaning it will slightly dry on top.