Preheat your oven to 350°F. While it’s heating up, butter two 9-inch round cake pans.
Then line the bottom of each with a round of parchment paper. Don’t forget to butter the parchment too, and give the pans a light dusting of flour—just shake out the extra so it doesn’t clump.
Now grab a mixing bowl and sift in the cake flour. Add the baking powder, baking soda, and salt, then whisk it all together for about 20 seconds to mix it evenly.
In a separate small bowl, toss the blueberries with 1 tablespoon of that flour mixture—this helps keep them from sinking in the batter later. Set both the flour mix and the coated blueberries aside for now.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, granulated sugar, and lemon zest on high speed.
Let it whip for about 3 minutes until it’s super light, fluffy, and pale—like a cloud! ☁️ Don’t forget to scrape down the sides of the bowl so everything gets mixed in evenly.
Now add the eggs one at a time, mixing well after each one. Stir in the vanilla extract, then give the bowl another good scrape to keep things nice and smooth.
Grab a 2-cup liquid measuring cup and pour in the milk. Stir in the sour cream and lemon juice until it’s all nicely combined—easy and creamy!
Add one-third of the flour mixture to your butter and egg mixture, and mix just until everything comes together—don’t overmix! Next, pour in half of the milk mixture and mix again just until combined.
Repeat by adding another third of the flour, then the rest of the milk mixture, mixing just enough each time to keep the batter smooth. Finish it off with the last third of the flour mixture.
Now, gently fold in those flour-coated blueberries with a spatula—be gentle so they don’t burst and turn your batter purple!
Divide the batter evenly between your prepared pans and spread it out so the tops are nice and smooth.
Pop them into your preheated oven and bake for 30 to 35 minutes, or until a toothpick poked into the center comes out clean—no gooey batter means they’re done!
Let the cakes cool in their pans for about 20 minutes. Then run a knife around the edges to make sure they’re loosened up.
Carefully flip them out onto wire racks and let them cool completely—no rushing here, you don’t want the frosting to melt!
Once the cakes are totally cool, spread on that delicious cream cheese frosting.
Store your frosted cake in an airtight container in the fridge. When you're ready to serve, let it sit at room temp for a bit so it’s soft and dreamy.