Preheat your oven to 350 degrees Fahrenheit. It’s essential to have your oven ready so that your cake bakes evenly. Spray a 9×13 glass casserole dish with cooking oil to prevent sticking.
In a large mixing bowl, combine the yellow cake mix, water, oil, and eggs. Use a whisk or an electric mixer to blend until the batter is smooth and homogenous. Look for a silky texture that’s free of lumps.
Once mixed, pour the batter into the prepared baking pan, spreading it evenly. Bake for 30 to 32 minutes or until a toothpick inserted in the center comes out clean. The cake should be golden brown, and the edges might slightly pull away from the sides of the pan.
After baking, allow the cake to cool for at least 45 minutes. It should feel cool to the touch before you proceed to the next step, ensuring that your filling will not melt.
In another mixing bowl, add the cream cheese and sweetened condensed milk. Mix them together until you achieve a smooth consistency. This step is best done with an electric mixer, but you can mix by hand if the cream cheese is really soft.
In a medium bowl, whisk together the lemon pudding mix, milk, and lemon juice. Ensure that it’s well combined and smooth before moving on.
Mix the lemon pudding mixture into the cream cheese mixture, blending well until fully combined. Then, gently fold in about 6 ounces of the Cool Whip, ensuring you don’t deflate the mixture.
Using the handle of a large spatula or spoon, poke holes into the cooled cake in even rows, creating a grid pattern. This allows the filling to seep into the cake, making it extra moist.
Spread the lemon filling over the cake, pushing it gently into the holes. Use a spatula to smooth it out evenly, topping with the remaining Cool Whip.
Crush five of the lemon Oreos into large crumbs and sprinkle them over the top of the cake. This adds a lovely crunch and enhances the lemon flavor.
Refrigerate the cake for at least 2 hours to let the topping set. When ready to serve, garnish with half a cookie and a twist of lemon, if desired. Enjoy this delightful treat!