01 - Preheat oven to 350°F. Grease and line three 8-inch round cake pans with parchment paper.
02 - Whisk together flour, baking powder, baking soda, and salt in a bowl.
03 - Beat butter, sugar, and lemon zest in a large bowl until light and fluffy.
04 - Beat in eggs one at a time, then add lemon juice and vanilla extract.
05 - Alternate adding flour mixture and buttermilk, beginning and ending with flour. Mix until just combined.
06 - Divide batter evenly among prepared pans. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. Cool in pans 10 minutes, then turn out onto wire racks to cool completely.
07 - Combine strawberries, sugar, and lemon juice in a saucepan. Cook over medium heat until strawberries release juices, about 5 minutes.
08 - Mix cornstarch and water; stir into strawberries. Cook, stirring constantly, until thickened, 1–2 minutes. Remove from heat and cool completely.
09 - Beat cream cheese and butter until smooth. Gradually add powdered sugar, then lemon juice, zest, vanilla, and salt. Beat until fluffy.
10 - Place one cake layer on a serving plate. Spread half of the strawberry filling over the top, avoiding the edges. Add a layer of frosting to prevent the filling from seeping out.
11 - Repeat with the second layer, adding remaining strawberry filling and a frosting barrier.
12 - Top with the final cake layer. Frost the top and sides with remaining lemon cream cheese frosting.
13 - Chill cake for at least 30 minutes before slicing for neat layers.