1️⃣ Make the Blueberry Filling:

• In a saucepan, combine all ingredients and bring to a simmer. Stir constantly for 5-10 minutes until thickened.
• Remove from heat and let cool—it will thicken more as it cools.

2️⃣ Make the Lemon Cake:

• Preheat oven to 350°F and line two 8″ baking pans with parchment paper.
• In a bowl, mix flour, baking powder, and salt.
• In a large bowl, beat butter, oil, and sugar until creamy. Add eggs one at a time, mixing well.
• Alternately add dry ingredients, milk, lemon juice, and more dry ingredients. Stir in vanilla and lemon zest.
• Divide batter evenly into pans and bake for 28-32 minutes (until a toothpick comes out clean). Let cool.

3️⃣ Make the Frosting:

• Beat butter until creamy, then mix in cream cheese until smooth.
• Gradually add powdered sugar, stirring until creamy.
• Add lemon juice one tablespoon at a time, adjusting consistency as needed.

4️⃣ Assemble the Cake:

• Cut cake layers in half horizontally.
• Place one layer on a plate, spread frosting around the edges, and fill with blueberry filling. Repeat for remaining layers.
• Lightly frost the outside, then chill for 4 hours before serving.