Preheat oven to 400°F. Line a baking sheet with parchment paper or a silicone baking mat. Set aside.
Whisk together dry ingredients in a large bowl: flours, pudding mix, cornstarch, baking soda, baking powder and salt.
1 1/2 cups All-Purpose Flour, spooned and leveled, 1 cup Cake flour, spooned and leveled, 3.4 oz. Instant Pudding Mix (Vanilla), 1 tsp. corn starch, 1/2 tsp. baking soda, 1/2 tsp. baking powder, 1/2 tsp. salt
Place cubed butter and sugars into bowl of a stand mixture and secure the paddle attachment. Turn mixer on and cream until smooth, about 1-2 minutes.
8 Tbsp. unsalted butter, cold, cubed, 1/2 cup packed brown sugar (light or dark), 1/4 cup granulated sugar
Add in eggs and vanilla extract and blend until mixed. Use a rubber spatula to knock off mixture if any is sticking to the sides of the bowl and mix again.
1 Tbsp. vanilla extract, 2 large eggs
Gradually add in the dry ingredients, about 1/4 cup at a time. Then add in the frozen chopped Twix pieces and mix just until combined.
8 oz. Twix, frozen and cut into pieces
Roll cookie dough into balls and place on prepared cookie sheet. Press down a little if you want since these do not spread very much. You can make giant cookies, or make into smaller sized cookies. Bake for 10-11 minutes. Allow cookies to cool while you make caramel and chocolate layer.