Step 1: Preheat the Oven
Preheat your oven to 325°F (163°C). Grease and flour a bundt pan or a loaf pan and set aside.

Step 2: Cream the Butter and Sugar
In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy. This should take about 3–5 minutes.

Step 3: Add the Eggs
Add the eggs one at a time, beating well after each addition. This ensures a smooth and creamy batter.

Step 4: Combine the Dry Ingredients
In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.

Step 5: Mix the Wet Ingredients
In a small bowl, mix the buttermilk, key lime juice, zest, and vanilla extract.

Step 6: Incorporate the Dry and Wet Mixtures
Alternate adding the dry ingredients and the buttermilk mixture to the butter mixture, beginning and ending with the dry ingredients. Mix until just combined—don’t overmix!

Step 7: Pour and Bake
Pour the batter into the prepared pan. Smooth the top with a spatula. Bake for 70–80 minutes or until a toothpick inserted into the center comes out clean.

Step 8: Cool and Glaze
Allow the cake to cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely. Drizzle with the lime glaze and sprinkle with additional zest if desired.