In a saucepan over medium heat, stir together the strawberries, sugar and water until the sugar is dissolved. Heat the mixture to boiling, stirring often. Reduce heat and add the vanilla and lemon juice.
In a small cup, combine the cornstarch and two tablespoons of water. Mix well.
Pour this into the boiling strawberry mixture. Stir and boil over medium-low heat for 4 minutes or until the mixture has thickened a bit.
Remove the pan from the heat.
Add 1 tablespoon of butter and mix until the butter has completely melted.
If you'd like your strawberry syrup to have a nice red color, add a few drops of red food coloring. This is completely optional.
Allow the mixture to cool for 15 minutes, then add the last cup of quartered, fresh strawberries.
Set aside until the cake is done.
For the Cake:
Preheat oven to 350. Grease and flour a 13x9 pan.
In a large bowl, mix the cake mix, eggs, oil and milk. Beat on low speed for 2-3 minutes, scraping the bowl as needed.
Pour the batter into the prepared pan. Tap on counter to eliminate air bubbles.
Bake for 23-28 minutes, or until the center of the cake bounces back when you touch it.
Allow cake to cool for 15 minutes.
Using the end of a wooden spoon, poke 20-25 holes into your cake.
Pour cooled strawberry mixture over the cake and spread it evenly.
For the Whipped Cream:
In a large, clean mixing bowl, whip the cold heavy cream until stiff peaks form. This works best when the cream is very cold. You can refrigerate a metal bowl to beat it in also.
Fold the whipped cream into softened (but not melted) frosting.
Spread the whipped frosting evenly on the cake.
Cover the cake and store the cake in the refrigerator.
The calories shown are based on the cake being cut into 15 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.