Preheat your oven to the temperature indicated on the cake mix package and grease a 9x13-inch baking dish

Prepare the cake mix according to package instructions.  Transfer the batter to the greased baking dish and bake according to the instructions.

Let the baked cake cool for at least 15 minutes. Once cooled, use a fork or skewer to poke evenly spaced holes, approximately 1 inch apart, across the surface.

Dissolve the Jello powder completely by stirring it into 1 cup of boiling water in a mixing bowl.   mixed until completely dissolved, then add 1 cup of cold water and mix well.

gently pour the Jello mixture evenly over the cake, ensuring it seeps into the holes.

Cover the cake with plastic wrap and refrigerate for at least 3 hours or until the Jello is set.

Before serving, spread whipped topping over the cake. Add a decorative touch with fresh fruit or sprinkles as desired.