Preheat your oven to 350°F (175°C). Grease and flour a 9x13-inch baking dish.
Prepare the cake mix according to package instructions. Pour the batter into the prepared dish and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool for 10 minutes.
In a medium bowl, dissolve the strawberry gelatin mix in 1 cup of boiling water. Stir until fully dissolved, then add 1 cup of cold water.
Using the handle of a wooden spoon, poke holes all over the surface of the cake. Pour the prepared gelatin mixture over the cake, ensuring it seeps into the holes.
Refrigerate the cake for at least 2 hours to set.
Spread the whipped topping evenly over the chilled cake. Garnish with fresh strawberries if desired.
Slice and serve chilled for the best flavor and texture.