Preheat the oven to 350 degrees F and spray two 9-inch round baking pans with baking spray.
In bowl of stand mixer fitted with whisk attachment, place the butter, sugar and lemon zest. Beat until light and fluffy.
In a separate bowl, mix together dry ingredients and set aside.
With the mixer on low speed, add the eggs, one at a time, combining thoroughly in between. With the mixer still running, add the lemon juice. (batter will look curdled, but it's not). Add one third of the dry ingredients and 1/2 cup of the buttermilk. Mix, then stop and scrape the sides of the bowl. Repeat, adding another third of the dry ingredients and the remaining 1/2 cup buttermilk. Mix, then stop and scrape. Add the remaining third of the dry ingredients and mix until completely combined and the batter is light and fluffy.
Divide the batter evenly between the prepared pans. Bake the cakes for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let the cakes cool before removing from the pans.
While the cakes are cooling, make the strawberry buttercream frosting. Combine the butter and powdered sugar in a large bowl or standing mixer. Mix together on medium speed until pale and fluffy, about 3 minutes. Add the milk and strawberries and mix on high speed until the frosting is very fluffy and pale pink in color, with flecks of strawberry.
Invert one of the cake rounds onto a cake plate; generously spread with frosting and top with strawberry slices. Repeat with the remaining layer of cake and frosting. Frost the sides of the cake. Put in the refrigerator for about 30 minutes to allow the frosting to set. Serve at room temperature.