Preheat oven to 350 degrees F. Coat a 13- x 9-inch baking dish with nonstick cooking spray.
Prepare the cake as instructed on the box mix with the eggs, water, and oil. Bake in the prepared baking dish for 28 to 30 minutes, or until a toothpick inserted in the center comes out clean.
Just before removing the cake from the oven, place the Jello in a small bowl and add the boiling water. Stir for about 2 minutes or until it is completely dissolved. Set aside.
Remove the cake from the oven and cool on a wire rack for 5 minutes (allow dissolved Jello to cool just slightly while the cake is cooling). Using a wooden chopstick or skewer, pierce holes in the top of the cake about ¾ of the way down, about 1- to 1-½ inches apart, and to within 1-inch of the edge. If using a thin skewer, twist it gently to make slightly larger holes. Gradually pour the jello mixture over the cake, being careful to fill each hole. Cool 15 to 30 minutes, just until bottom of the cake pan has cooled a bit, then carefully cover with foil so you don't disturb the top of the cake. Refrigerate for 2 hours or overnight.
In a large bowl with a wire whisk, combine the pudding mix with the milk and vanilla, whisking well until smooth. With a wooden spoon or rubber spatula, gently fold in the whipped topping until no streaks remain. Spread the frosting evenly over the chilled cake. Serve immediately or refrigerate, uncovered, for several hours, if needed.
Scatter the fresh strawberries over the frosting just before serving.