Preheat oven to 350°F (177°C). Grease three 6-inch cake pans or two 8-inch cake pans and line the bottoms with parchment paper.

In a large mixing bowl, add the granulated sugar and lemon zest. Use your fingers to rub the zest into the sugar until it becomes fragrant and slightly damp.

Add the eggs to the lemon sugar and whisk for about 1 minute until slightly pale. Slowly stream in the oil while whisking until fully combined and smooth.

Whisk in the buttermilk, lemon juice, vanilla extract, and lemon extract (if using).

Add the cake flour, baking powder, baking soda, and salt directly into the bowl. Whisk just until combined and smooth. Do not overmix.

Divide batter evenly between the prepared pans. Bake 25-30 minutes or until a toothpick inserted into the center comes out clean or with a few moist crumbs.

Allow cakes to cool in the pans for 10 minutes, then turn out onto wire racks to cool.

While the cakes are baking, combine lemon juice and sugar in a small saucepan. Warm over low heat until the sugar completely dissolves. Brush the syrup lightly over warm cake layers using a pastry brush. Allow the cakes to completely cool before frosting.

Beat cream cheese and butter together for 2–3 minutes until smooth and creamy.

Add powdered sugar one cup at a time, mixing on low speed until incorporated.

Mix in lemon juice, vanilla, and salt. Beat until smooth and fluffy.

Level cake layers if needed, and place the first layer on a cake stand or plate. Spread frosting evenly over the top. Add the next layer and repeat. Frost the outside of the cake as desired. Garnish with fresh lemon zest or thin lemon slices.