Last month I attempted to make a cake in high humidity using my regular buttercream recipe. the results were far from ideal. The cake fell apart (check out the photo). I had to make a cake this last weekend in the horrible E Texas 100% humidity. This time I used a different recipe and it worked out great.
1/2 cup solid vegetable shortening
1/2 cup (1 stick) butter softened
1 teaspoon clear vanilla extract
4 cups (approx. 1 lb.) confectioners' sugar sifted (name brand works best!)
2 tablespoons milk
2 tablespoons cornstarch
Makes: About 3 cups.
In large bowl, beat shortening and butter with electric mixer until light and fluffy. Add vanilla; mix well. Gradually add sugar, one cup at a time, beating well on medium speed. Scrape sides and bottom of bowl often. When all sugar mixture has been mixed in, icing will appear dry. In small bowl, combine milk and cornstarch; stir until cornstarch is dissolved. Add to icing mixture; beat at medium speed until light and fluffy.
Keep icing covered with damp cloth until ready to use. For best results, keep icing bowl in refrigerator when not in use. Refrigerated in an airtight container, this icing can be stored 2 weeks. Re-whip before using.