Preheat the oven to 375°F. Grease a standard muffin pan, or line with greased cupcake papers., To make the cupcakes: In a large mixing bowl, combine the flour, sugar, Cake Enhancer, baking powder, and salt. Add the butter and mix until the mixture is crumbly., Whisk together the eggs, milk, and vanilla. Add to the dry ingredients in two additions, mixing well in between. Scrape the bowl, mix briefly, then scoop the batter into the prepared pan, using 1/3 cup for each well., Bake the cupcakes for 16 to 18 minutes, until lightly browned and a toothpick or cake tester inserted in the center comes out clean., Remove the cupcakes from the oven and let them cool in the pan for 5 minutes; after 5 minutes, gently tilt them out of the pan and place on a rack to finish cooling completely., To make the frosting: In a medium bowl, beat together the butter, shortening, and salt. Add 4 cups of the confectioners’ sugar, the vanilla, and 2 tablespoons of the milk. Beat until fluffy, adding more milk or confectioners’ sugar as needed to achieve the desired consistency., Use a cupcake corer or small spoon to scoop some of the center out of each cupcake. Fill and frost with the frosting., Store at room temperature in an airtight container for two days; freeze for longer storage.