Preheat the oven to 325°F.
Grease a 6-inch round pan with butter, line the bottom with parchment paper and grease the paper.
Add the lemon juice to the milk to sour it. Set aside for 5 to 10 minutes or until curdled.
In a small bowl, whisk the eggs together. Set aside.
In another small bowl, use your fingers to work the vanilla bean seeds into the sugar. Remove any bits of the pod that may have come off with the seeds. Set aside. If you don't have any vanilla beans, add 2 tsp of vanilla extra to the sugar and mix with a fork. It will look like wet sand.
Place a large sifter in a large mixing bowl. Add the flour, baking powder, baking soda, and salt and sift. I sifted my dry ingredients three times, this may be overkill but I would sift it at least twice. This will help make your cake light and fluffy.
Using a stand mixer with a paddle attachment, beat the butter for 30 seconds at medium speed and then gradually add the vanilla sugar. Scrape down the sides of the bowl. Continue beating on medium speed for another 4 minutes or until light in color and fluffy.
Add the vanilla extract and beat until combined.
With the mixer still at medium speed, gradually add the eggs. If the batter curdles, add 1 to 2 tablespoons of the flour mixture to bind it back together.
At low speed, add the flour mixture and then the oil and milk; mix until just combined. Don’t overbeat. Scrape down the sides and bottom of the bowl.
Pour the batter into the prepared pan and smooth the top. Bake in the center of the oven for 50 to 55 minutes. When a wooden skewer inserted into the center comes out clean, and the cake bounces back when lightly pressed, remove the cake from the oven and let it stand for 10 minutes. Run a butter knife around the cake to gently release. Peel off the parchment paper from the bottom, and cool on a wire rack.
