Preparation Steps

• Preheat the oven to 350°F (175°C). Grease and flour two 8-inch round cake pans and line the bottoms with parchment paper.
• In a medium bowl whisk together the all-purpose flour, baking powder, baking soda and salt; set aside.
• In the bowl of a stand mixer cream the softened butter and granulated sugar together on medium-high speed until light and fluffy, about 3 to 4 minutes.
• Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and lemon zest.
• With the mixer on low, add the dry ingredients in three additions alternating with the buttermilk and vegetable oil, beginning and ending with the dry ingredients. Mix until just combined; do not overmix.
• Stir in the fresh lemon juice by hand until evenly distributed. Divide batter evenly between prepared pans and smooth the tops.
• Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean. Let cakes cool in pans for 10 minutes, then invert onto a wire rack to cool completely.
• Meanwhile make the lemon filling: Beat 0.5 cup softened butter with 1 cup powdered sugar, then add 0.25 cup fresh lemon juice and beat until smooth. Adjust thickness with more powdered sugar if needed.
• For the lemon butter frosting: Beat 1 cup softened butter until creamy. Gradually add 4 cups sifted powdered sugar on low speed. Add 0.25 cup lemon juice, 2 tablespoons heavy cream and 0.5 teaspoon salt; beat on medium-high until light and fluffy, adjusting consistency with cream or powdered sugar.
• Level the cooled cake layers if necessary. Place one layer on a serving plate, spread the lemon filling evenly over it, then top with the second cake layer.
• Frost the top and sides of the cake with the lemon butter frosting. Garnish with extra lemon zest or thin lemon slices if desired.
• Chill the cake for 30 minutes to set the frosting before slicing. Store covered at room temperature up to 2 days or refrigerate for up to 5 days.