Preheat the oven to 350F and grease and flour your cake pan
Whisk the flour, baking powder, baking soda, salt, and cornstarch in a bowl and set aside.
Whip the butter/oil and sugar together till well combined
Mix in Lemon Zest
Now add the eggs and yolk in three additions, mixing really well between each. The batter will become fluffier.
Add the lemon juice to the buttermilk.
With the mixer on low add half the dry ingredients, then half the buttermilk mix, then the remaining dry ingredients and finally the remaining buttermilk.
Turn the speed up just a little to combine, stopping to scrape the sides with a spatula. Don't overmix - your batter will be thicker if you used butter and runnier if you use oil.
Pour the batter into your prepared tin and bake for 40-45 minutes or until a skewer inserted in the middle comes out clean. I suggest peeking in at the 35 minute mark because oven temperatures can vary.
Let the cake cool in the tin for a few minutes then invert onto your cake plate
Cream Cheese Glaze
In a small bowl mix the cream cheese until smooth
With the mixer on low add 1 cup of icing sugar and lemon juice and mix until it incorporates into the cream cheese mix
Whisk in 3 tbsp of cream or 2 tbsp of milk.
Spread the icing on your cake with a spoon and decorate with your favorite fruit or a little lemon zest or just leave it as is!
Notes
Notes:This amount of sugar produces a sweet and tart lemon cake. If you like your cakes less sweet then I recommend dropping the sugar to 1 cup.Please read the post for buttermilk substitutes, a comparison of oil and butter, and why I use cornstarch (which you can omit if you don't have it)