Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan. In a large bowl, combine white cake mix, 1 cup water, vegetable oil, and eggs. Mix until just combined; do not overmix. Pour batter into prepared pan.

Bake according to cake mix box instructions (usually 30-35 minutes), or until a toothpick inserted into the center comes out clean. Let cool in pan on a wire rack for 10-15 minutes.

While cake cools, prepare Jello. In a heatproof bowl, add strawberry Jello to 1 cup boiling water. Stir vigorously for at least 2 minutes until dissolved. Stir in 1/2 cup cold water.

While cake is still warm but not hot, poke holes all over the surface with the handle of a wooden spoon or skewer, about 1-inch apart, going all the way to the bottom. Pour the prepared strawberry Jello mixture evenly over the cake, allowing it to seep into the holes.

Transfer cake to the refrigerator and chill for at least 3-4 hours, or preferably overnight, until the Jello is fully set.

Once Jello is set and cake is chilled, remove from refrigerator. Spread whipped topping evenly over the Jello. If using, sprinkle chopped fresh strawberries over the whipped topping.