Preheat your oven to 350°F (175°C). Grease and flour the 9x13-inch baking dish.
In a large mixing bowl, combine the strawberry cake mix, water, vegetable oil, and eggs. Mix until well combined, about 2 minutes.
Pour the batter into the prepared baking dish and bake for 30 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool completely in the pan.
Once the cake has cooled, use a fork or a wooden spoon handle to poke holes all over the top of the cake, about 1 inch apart.
In another bowl, whisk together the strawberry gelatin and boiling water until completely dissolved, then pour the mixture evenly over the cake, allowing it to seep into the holes.
In a separate bowl, combine the cold milk and instant vanilla pudding mix. Whisk until thickened, about 2 minutes. Fold in the whipped topping until smooth.
Spread the pudding mixture evenly over the cake. Sprinkle the crushed cookies or wafers on top to create the crunchy layer.
Cover the cake with plastic wrap or aluminum foil and refrigerate for at least 2 hours, or overnight for the best flavor and texture.
Before serving, garnish with fresh sliced strawberries if desired. Cut the cake into squares and enjoy!