Preheat your oven to 350°F / 177°C, meanwhile, place a metal mixing bowl and the beaters from a hand mixer into the freezer.

In a mixing bowl, combine 2 ¾ cups flour, ¼ cup potato starch, 1 teaspoon baking powder, 1 teaspoon salt, and 2 tablespoons key lime zest. Whisk together until fully combined and set aside.

Next, add your 5 whole eggs in, one at a time, ending with the two egg yolks, still mixing at a medium-low speed the whole time. Once fully combined, add in some of the dry mixture, followed by some of the buttermilk. Continue mixing at a medium speed while alternating the dry mixture and the buttermilk until you’ve used all of both.

Remove the bowl and beaters from the freezer and pour in the ½ cup of heavy whipping cream. Begin mixing at low speed, gradually increasing the speed as it thickens. Once you’re just passed the soft peak stage (just like in the photo above), begin adding the whipped cream to the batter, folding it in by hand with a spatula.

Now setup a 12 cup Bundt pan for your batter. Use a baking spray that contains flour, like Baker’s Joy, or use butter to completely coat the inside of the pan, then coat with flour and shake out the excess. The better you do here, the cleaner your pound cake will come out at the end.

Pour the batter into the Bundt pan and smooth it out with a spatula. Now lift the pan about an inch or so off your counter and drop it. Repeat 2-3 times. This helps level everything out, but should also dislodge any air pockets you may have added when pouring the batter in. Place in the center rack of your oven and cook for about 1 hour to 1 hour 15 minutes. Begin checking around the 50-minute mark and remove when a toothpick comes out mostly clean (a few moist crumbs is fine).

While the pound cake is baking, prepare your soaking solution if using. In a small saucepan, combine ¼ cup of key lime juice with a ¼ cup of white granulated sugar. Set over medium heat and stir until the sugar is fully dissolved. Keep stirring until it just starts to simmer and then remove from the heat and set aside. Wait to do this step until the baking is almost done. The soaking solution doesn’t need to be hot but should still be warm when you apply it.

Once the pound cake has cooked, remove it from the oven and place the entire Bundt pan on a cooling rack set over some wax or parchment paper. Wait about 5-10 minutes for the pan to cool, then set it on your counter, flip the cooling rack over and lay it on top of the Bundt pan. Now, while holding the cooling rack with one hand, grip the side of the Bundt pan and flip the whole thing over and the pan should lift off the pound cake cleanly. If it doesn’t come out easily, reverse the process and try lightly banging the side of the pan on the edge of your counter a few times, then try again.

As soon as you remove the key lime pound cake from the pan, use a pastry brush and begin brushing the soaking solution all over the outside of the pound cake. Be sure to coat the entire cake, including the sides and the smaller inside hole as well. Repeat this process 4-5 times until most or all the solution has been used. Now, allow the pound cake to cool completely before adding the glaze, about an hour.

If using the glaze, wait until the key lime pound cake has cooled, then make your glaze. In a bowl, combine 1 cup of sifted confectioner’s sugar with 2 tablespoons of key lime juice and mix with a spoon until it’s fully mixed and the consistency of a slightly thin paste. Spoon the mixture slowly over the top of the pound cake and let it go down the sides naturally. For best results, wait for the glaze to harden slightly at room temperature for at least 30 minutes to an hour before serving.