Sarah's Italian Meringue Buttercream
If syrup looks crystallized in step 2, it is because it was heated too quickly and you will need to start the syrup over. If buttercream looks curdled in step 4, continue to beat until smooth.
Vanilla Bean: Beat in seeds scraped from 1 vanilla bean pod
Chocolate: Beat in 1/2 cup semisweet chocolate that has been melted and cooled
Raspberry or strawberry: Beat in 1/4 to 1/2 cup raspberry or strawberry puree
Other flavors: Add 1 to 2 teaspoons flavor extract