Prepare a 9x13 pan by spraying with non-stick cooking spray. Preheat oven to 350°.
To create the sugar cookie crust, combine the butter and sugar in the bowl of a stand mixer. Cream for 3 minutes.
Scrape sides and add in eggs and vanilla. Mix throughly.
Add flour to the bowl and mix until combined. It will be a very wet dough, or a stiff batter. Kind of in between.
Spread the batter onto the bottom of the greased 9x13 pan.
Bake at 350° for 15 minutes or until the top is puffy and no longer has the 'dough' look.
For the cream cheese layer, whip together the cream cheese and powdered sugar.
Once whipped, gently fold it into the Cool Whip. Spread over the cooled sugar cookie crust.
For the Vanilla Cool Whip layer, combine the butter, powdered sugar, milk and vanilla together in the bowl of a stand mixer.
Whip for 3-5 minutes, or until light and fluffy.
Fold the buttercream together with the Cool Whip. Spread over the cream cheese layer.
For best results, refrigerate for 1 hour before serving.