Set the oven to 325 degrees F.

With a heavy-duty electric stand mixer, beat the butter and shortening at medium speed until creamy. Then, slowly add the sugar, beating well until light and fluffy. Next, add the eggs (a piece at a time), beating every after each addition until just blended.

Combine the flour with baking powder and salt. Alternately add this and the milk to the butter mixture, starting and ending with the flour mixture. Beat on low after each addition until combined. Then, mix in the vanilla, lime zest, and lime juice.

Transfer the batter to a greased and floured 10-inch or 12-cup tube pan.

Place in the preheated oven and bake the cake for 1 hr 15 min to 1 hr 20 min or until a cake tester inserted in the middle of the cake comes out clean. Remove from the oven and place on a wire rack to cool. Let the cake cool in the pan for 10 – 15 minutes. Then, invert the cake onto the wire rack.

Key Lime Glaze: Mix the powdered sugar, fresh Key lime juice, and vanilla until smooth. On top and sides of the cake, immediately brush the glaze and cool for about an hour.