Key Lime Pound Cake

Garnish a traditional lime muffin with a little lime zest and homemade lime frosting for a delicious tropical dessert.
Preheat the oven to 325 degrees. Beat the butter and shortening on medium speed using a powerful electric mixer until creamy. Gradually add the sugar, whisking on medium speed until light and fluffy. Add the eggs 1 at a time, whisking after each addition until smooth.Combine flour, baking powder and salt. Add the milk alternately to the butter mixture, starting and ending with the flour mixture. Beat on low speed until smooth after each addition. Add vanilla, lime zest and lime juice. Pour the batter into a 10-inch diameter (12-cup) greased and floured baking dish.Bake at 325 ° C for 1 hour 15 minutes to 1 hour 20 minutes, or until a long wooden stick inserted in the middle comes out clean. Cool in the pan on a wire rack for 10-15 minutes; transfer from the pan to a wire rack.Prepare the lime frosting and immediately spread it on the top and sides of the cake. Allow to cool completely (about 1 hour).