Preheat oven to 350°. Spray a mini muffin tin with non stick spray. Set aside.
Combine the white cake mix, oil and eggs. Mix until the cookie dough forms. It will be very soft and sticky.
Separate the dough evenly into the prepared mini muffin tin.
Bake at 350° for 8-10 minutes or until the cookies just start turning brown.
Immediately after removing from the oven, use the back of your teaspoon measuring spoon to push down in the center of the cookies creating the 'cup'.
Once all of the cookies have been pressed and made into a cup, set aside and let them cool completely.
While the cookies are cooling, make the creamy vanilla filling.
Combine the butter, milk, powdered sugar and vanilla. Mix until creamy and smooth.
Add the cool whip, mix thoroughly.
Either pipe or spoon the filling into the cooled cookie cups.
Right before serving, top with the diced strawberries.
Store in the fridge.