This does not contain cornstarch, but is a wonderful old recipe for lemon cake, delicious warm, with the syrup poured over:

Hot Lemon Cake

Mix until smooth:
3 tablespoons butter
3 tablespoons shortening
1 cup sugar
rind of one lemon
Add:
2 eggs, one at a time, beating well after each addition
Then add:
(alternating between milk and flour starting and ending with flour):
1 1/2 cups flour sifted with 1 teaspoon baking powder
1 cup milk

Pour into greased cake pan (I use a bundt pan).

Bake at 350 F for 45 minutes. Unmold while warm.

Then mix:
juice from one lemon
1/4 cup sugar

Using a fork, poke holes in top of cake and pour lemon syrup into holes.