Preheat the oven to 350 F. Spray a 9x13 baking pan with baking spray and set aside.
In a large mixing bowl, whisk the cake mix and vanilla pudding together.
Add in the vegetable oil, milk, water, eggs and egg yolk and whisk just until combined.
Pour the cake batter into the prepared cake pan.
Place into the oven to bake for 28-30 minutes or until a toothpick inserted comes out clean.
Remove from the oven and place onto a cooling rack to cool for 15 minutes.
While the cake is cooling, whisk together the powdered sugar and lemon juice. Once the cake has cooled, using a chopstick or end of a wooden spatula to poke holes throughout the entire cake. Be sure to poke enough holes so that the cake is able to absorb the lemon glaze and sweetened condensed milk but don’t poke so many that the cake will fall apart.
Pour the lemon glaze over the surface of the cake. Pour the sweetened condensed milk over the cake and spread with a rubber spatula or back of a spoon.
Cover and place the cake into the fridge to cool for 2 hours. Add the strawberry jello to the cool whip and fold it together.
Once the cake has chilled, spread the strawberry cool whip over the cake. Top with sliced strawberries.