I really like this one. It pipes pretty well for decorations, but haven't made any flowers with it. Give it a whirl!
6 (1 ounce) squares white chocolate, chopped
2 1/2 tablespoons all-purpose flour
1 cup milk
1 cup butter, softened
1 cup white sugar
1 teaspoon vanilla extract
In a medium bowl, combine 6 ounces white chocolate, 2 1/2 tablespoons flour and 1 cup milk. Cook over medium heat, stirring constantly, until mixture is very thick. Cool completely.
In large bowl, cream 1 cup butter, 1 cup sugar and 1 teaspoon vanilla; beat until light and fluffy. Gradually add cooled white chocolate mixture. Beat at high speed until it is the consistency of whipped cream.