• Preheat the oven to 350 degrees and line three 6-inch cake pans with parchment paper then nonstick spray. Set aside.

Lemon Cake

• In a medium-sized bowl, whisk together the flour, baking powder, and salt. Set aside.
• In the bowl of an electric stand mixer using the paddle attachment, cream together the sugar, butter, and vegetable oil on med-high speed until fully combined and fluffy (about 2-3 minutes). Scrape down the sides of the bowl as needed.
• Reduce the speed to medium and mix in the lemon juice, lemon zest, yogurt, and vanilla extract just until combined. Add the eggs, one at a time, beating well after each addition. Then mix for 1 minute (the mixture will look like it has separated and that's okay!).
• Reduce the mixer speed to low and alternately add the flour mixture and milk, starting and ending with the flour (flour, milk, flour) and mixing just until combined. Remove the bowl from the stand mixer and fold in any loose ingredients with a silicone spatula.
• Divide the batter amongst the three prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted into the middle of the cakes come out clean. Let the cakes cool in the pan for 25 minutes before removing and placing them on a wire rack to cool completely.

Blackberry Jam

• In a medium-sized saucepan over medium heat, mix together the blackberries, sugar, and lemon juice. Occasionally stir until the berries have broken down and the jam has thickened (about 15-20 minutes). You can squish the berries as they cook to quicken up the process.
• Once thickened, transfer the blackberry jam to a heat-safe bowl and place it into the refrigerator to completely cool.

Lemon Cream Cheese Frosting

• In the bowl of an electric stand mixer using the paddle attachent, beat the butter and cream cheese on high speed until light and creamy (1-2 minutes). Add the powdered sugar, lemon zest, lemon juice, and vanilla extract and mix on low speed until combined.
• Increase the speed to high and beat the frosting until smooth and creamy (1-2 minutes).

Assemble

• Place one cake layer on a cake stand or plate and pipe a border of frosting around the edge of the cake. Then spread 3-4 tablespoons of the blackberry jam in the center of the cake using an offset spatula.
• Repeat with the second layer. Top the cake with the last layer and spread on about ¼ cup of frosting. Frost and smooth the outside of the cake with a thin crumb coat. Place the entire cake in the refrigerator or freezer for 10 minutes to chill.
• Remove the cake from the refrigerator and finish frosting. Cover the sides and top of the cake again until frosted to your desire (use a cake scraper for a smooth finish). Place the cake in the freezer for 10 more minutes.
• I decorated the top by using the Wilton 6B to pipe a border and then added sliced lemons and fresh blackberries.
• Refrigerate the cake for at least 15 minutes before serving so it's easier to cut. Keep any leftover cake slices in an airtight container in the refrigerator for up to 5 days.