Grease and flour 3 8 inch round cake pans, or line with parchment paper.
Make the cake
In a large mixing bowl, beat butter and sugar together until light
Beat in eggs, vanilla, oil, lemon juice, lemon zest, and half the milk.
Add half the flour, along with baking powder and salt, and beat just until combined.
Add remaining milk, and beat until smooth.
Then beat in remaining flour, until everything is fully incorporated and smooth.
Divide batter evenly between prepared cake pans.
Bake for about 25 minutes, or until a toothpick inserted in the center comes out clean.
Remove from oven, and let cakes cool ten minutes on a wire cooling rack.
Then loosen the edges of the cakes from pans, and turn onto the wire rack to finish cooling.
Strawberry filling
Add strawberries, lemon juice, granulated sugar and cornstarch to a saucepan.
Heat over low-medium heat, mashing strawberries with a fork or potato masher. You can speed this up by using an immersion blender if desired.
Continue heating, and stirring until the strawberries are thickened into a sauce.
Remove from heat and set aside to cool.
Strawberry icing
Beat the softened butter and chopped strawberries until light and fluffy.
Mix in the milk.
Add the powdered sugar. Beat on low speed until the sugar is incorporated. Then increase speed to medium-high and mix until light and fluffy, 2 to 3 minutes.
Put the cake together
After the cake layers have completely cooled, level them if necessary.
Place bottom cake layer on cake board or plate.
Pipe a ribbon of icing around the edge of the layer, and fill center with half the strawberry filling.
Repeat with second layer.
Top with third layer.
Frost the top and sides of cake.
Top with sliced strawberries and lemon if desired.
Refrigerate until ready to serve.
Notes
Lining the bottom of the pan with parchment paper and greasing the sides makes sure that the cakes will come out of the pan easily.
If you only have 2 8-inch pans, fill one with ⅓ of the batter, and the other one with ⅔ of the batter. Then cut the thicker layer in half after it is baked. You will likely need to add a few minutes of baking time for the thicker layer.
If you don’t have a piping bag, use an offset spatula or knife to build a dam of icing around the sides of the cake. The main thing is, you don’t want the filling squeezing out of the cake edges when you’re trying to ice the outside.