• Preheat the oven to 350°F.

  Prepare 9x5-inch loaf pan by spraying with cooking spray or lining with parchment paper.
  
• Sift flour, baking powder, salt, and baking soda into a medium-sized mixing bowl and set aside.
  
• In the bowl of a stand mixer, use the paddle attachment to cream together the butter and sugar. Mix at medium speed until combined and then increase to medium-high until fluffy. This takes about 5-7 minutes. The mixture should be smooth and fluffy and there should be little to no graininess to it.
  
• Still using the paddle attachment, add the eggs one at a time, beating until well combined.

  Slowly add in the flour a little at a time, alternating with the buttermilk and mixing on low until a batter forms. Add vanilla, lemon juice, and lemon zest and mix on low until combined.
  
• Pour the batter into the loaf pan and bake for 30 minutes. Cover lightly with foil and bake an additional 20-25 minutes or until a toothpick poked into the center comes out clean.
  
• Allow cake cool for 20 minutes then remove the cake from the pan and cool the rest of the way on a wire cooling rack. Cake should be only slightly warm or room temperature before icing.
  

For the icing:

• Whisk together all ingredients until smooth. Pour evenly over the top of the cake. Pro tip: Use a baking sheet under the cooling rack to allow the extra icing to drip over the sides onto the sheet for an easier clean up.
  
• Allow to set before slicing.