Preheat oven to 350 degrees F. Prepare three 7-inch round cake pans with nonstick cooking spray and parchment paper circles.
In a large mixing bowl, whisk together all-purpose flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment or large mixing bowl with an electric hand mixer, cream room temperature unsalted butter, granulated sugar and vegetable oil for a few minutes until pale and creamy.
Add in eggs, one at a time, mixing on low speed in between each addition until well combined.
Add vanilla extract and lemon zest and continue to mix on low.
Add ⅓ of the flour mixture to the butter mixture. Mix on low speed until the dry ingredients are combined with the butter mixture.
Pour in half of the lemon juice and half of the milk. Mix on low speed until combined and smooth.
Add another ⅓ of the flour mixture and mix on low until combined. Add the remaining lemon juice and milk and mix until smooth.
Add the remaining flour mixture and mix on low speed until just combined. Scrape the sides and bottom of the bowl and mix an additional few seconds until the cake batter is smooth.
Portion the cake batter evenly among the prepared cake pans. Use a kitchen scale to create even layers.
Bake the cake layers in the oven for approximately 25-28 minutes until the tops of the cakes bounce back when gently touched.
Remove the cake pans from the oven. Allow the cake layers to cool in the pans for 10-15 minutes. Remove the cake layers from the pan and transfer to a wire rack to cool completely.