1 Lemon Cake Mix, baked according to directions in a 9x13 pan - (this can be a homemade lemon cake or a store-bought cake)
1 1/2 c. sugar
1/3 c. + 1 Tbs. Cornstarch
1 1/2 c. cold water
3 egg yolks, slightly beaten
3 Tbs. Butter
2 tsp grated lemon peel (fresh lemon is best, but dried lemon peel will work in a pinch)
1 tub cool whip or 2 c. Fresh Whipped Cream
In a medium size glass bowl, beat the egg yolks lightly, set aside nearby.
In a 2-quart saucepan mix sugar and cornstarch with a whisk. Turn on heat and immediately add cold water, whisking well. Cook over medium heat, whisking gently and constantly until the mixture thickens and begins to boil.
Boil, while stirring, for a full Minute. Remove from heat-
Temper the eggs carefully by immediately stirring at least 1/2 of the hot mixture into the eggs, (while stirring the eggs!) Stir the hot egg mixture back into the saucepan with the remaining mix, return to heat.
The mixture will be quite thick and bubbly, be careful it doesn't splatter you! Remove from heat- add butter, lemon peel and lemon juice, whisking gently until fully combined.
Let the mixture cool fully. Gently poke holes in the top of the cake with a shish-kebab stick. Pour the Lemon sauce over the tops of the cake, spreading it around evenly. Top with Cool whip or fresh whipped cream
Serve immediately or refrigerate for later. To make it pretty, add a few shavings of fresh lemon the top of the cream.
We generally prefer to use Real Lemon peel/zest in this recipe, it has much better flavor and texture.