Here's the Buttercream Frosting my Mom always uses on her wedding cakes
3 cups confectioners' sugar
1 cup butter
1 teaspoon vanilla extract
1 to 2 tablespoons milk (if necessary)
In a standing mixer fitted with a whisk, mix together sugar and butter. Mix on low speed until well blended and then increase speed to medium and beat for another 3 minutes.
Add vanilla and beat on medium speed for 1 minute more, adding milk if needed for spreading consistency.
The only problem is it doesn't give a true white color because of the butter. So if a bride wants a truly white cake - she will either use the 7 minute frosting (which is my fav anyway!) or roll a white fondant over it.
There's also one called Royal Icing - but it uses egg whites, too - but in the instructions I found, you can subbstitute powdered egg whites.
This is from Food Network:
Food Network Royal Icing "*2 large egg whites (or substitute powdered egg whites)
3 cups confectioners' sugar
1 teaspoon lemon juice
Combine the egg whites and confectioners' sugar in a medium-size mixing bowl and whip with an electric mixer on medium speed until opaque and shiny, about 5 minutes. Whisk in the lemon juice, this will thin out the icing. Beat for another couple of minutes until you reach the right spreading consistency for the cupcakes."