Step 1: Prepare the Oven and Pan
1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Grease Pan: Grease and flour a 10-inch bundt pan or loaf pan.

Step 2: Make the Cake Batter
1. Cream Butter and Sugar: In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
2. Add Eggs and Vanilla: Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
3. Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, and salt.
4. Mix Wet Ingredients: In another bowl, combine the sour cream, key lime juice, and lime zest.
5. Combine Mixtures: Gradually add the dry ingredients to the butter mixture, alternating with the sour cream mixture. Begin and end with the dry ingredients, mixing until just combined.

Step 3: Bake the Cake
1. Pour Batter: Pour the batter into the prepared bundt or loaf pan, smoothing the top with a spatula.
2. Bake: Bake in the preheated oven for 60–70 minutes, or until a toothpick inserted into the center comes out clean.
3. Cool: Once baked, remove the cake from the oven and let it cool in the pan for about 10–15 minutes before transferring it to a wire rack to cool completely.

Step 4: Prepare the Glaze
1. Mix Glaze: In a small bowl, whisk together the powdered sugar and key lime juice until smooth. Adjust the consistency by adding more lime juice or powdered sugar as needed.

Step 5: Glaze the Cake
1. Drizzle Glaze: Once the cake is completely cool, drizzle the glaze over the top. Garnish with additional lime zest if desired.