Pre-heat oven to 350 degrees. Mix cake mix as per directions on box. Pour into cupcake liners. Bake in oven as per directions on box. (Times may vary as each oven is different) Let cool before taking liners off.
Wash & slice strawberries, stir in sugar. Let sit until juice forms.
Beat pudding & milk in large bowl with whisk for 2 mins. Fold in Cool Whip until well blended together.
Once cupcakes are cooled, cut top off. Spread pudding mixture on both sides of the cut cupcakes. Spoon strawberries over one 1/2 of the cupcake, top with other 1/2. Spoon strawberries over and top with remaining Cool Whip if desired.