1. Prepare three 8 inch cake pans with parchment paper circles in the bottom and grease the sides. Preheat oven to 350°F (176°C).
2. Combine the flour, baking powder, baking soda and salt in a medium sized bowl and set aside.
3. Add the butter, oil, sugar and vanilla extract to a large mixer bowl and beat together until light in color and fluffy, about 1 1/2 to 2 minutes. Do not skimp on the creaming time.
4. Add the eggs one at a time, mixing until mostly combined after each. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
5. Add half of the dry ingredients to the batter and mix until mostly combined.
6. Combine the milk and lemon juice, then slowly add the mixture to the batter and mix until well combined.
7. Add the remaining dry ingredients and mix until well combined and smooth. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated. Do not over mix the batter.
8. Add the lemon zest and poppy seeds and gently stir to combine.
9. Divide the batter evenly between the cakes pans and bake for 22-25 minutes, or until a toothpick comes out with a few crumbs.
10. Remove the cakes from the oven and allow to cool for about 2-3 minutes, then remove to cooling racks to cool completely.
11. To make the frosting, add the cream cheese and butter to a large mixer bowl and beat until well combined and smooth.
12. Add about half of the powdered sugar and mix until well combined and smooth.
13. Add the lemon juice and zest and mix until well combined.
14. Add the remaining powdered sugar and mix until well combined and smooth. Add more or less powdered sugar, as desired for consistency purposes.
15. To put the cake together, use a large serrated knife to remove the domes from the top of the cakes so that they’re flat, if needed.
16. Place the first cake on a serving plate or a cardboard cake round.
17. Spread about 1 cup of frosting evenly on top of the cake.
18. Add the second layer of cake and another cup of frosting.
19. Top the cake with the remaining layer and frost the outside of the cake. Refer to my tutorial for frosting a smooth cake, if needed. To make the line pattern in the side of the cake, I used one of the decorative sides on this icing smoother.
20. Finish off the cake as you like. I added rosettes around the top outer edge and sprinkled on some poppy seeds. I also added some lemon slices.
21. Refrigerate the cake until ready to serve. Cake is best served cool, but not necessarily cold.