White Wedding Cake Cupcakes

Ingredients

• 1 (18.25 ounce) box white cake mix
• 1 cup all-purpose flour
• 1 cup granulated white sugar
• 3/4 teaspoon salt
• 1 1/3 cups water
• 2 Tablespoons vegetable or canola oil
• 1 teaspoon vanilla extract
• 1 cup sour cream
• 4 large egg whites