Preheat oven to 350°F. Spray a 9x13-inch baking dish with baker’s spray. Set aside.

In a large bowl, whisk the French vanilla cake mix, water, vegetable oil, and eggs together for 2 minutes. Follow the package instructions for baking in a 9x13-inch dish.

Pour the batter into the prepared baking dish and bake for 27 to 30 minutes or until a toothpick comes out clean.

Allow the cake to cool for 20 minutes. Poke holes over the entire surface with the handle of a wooden spoon.

Heat the blackberry preserves in the microwave for 45 seconds to 1 minute. Stir until pourable.

Pour the warmed preserves evenly over the cake, ensuring coverage in all holes. Use an offset spatula to smooth if needed.

In a large bowl, whisk together the white chocolate pudding mix and milk for 3 minutes or until thickened.

Fold in the whipped topping until fully combined.

Spread the pudding mixture over the cake, avoiding mixing into the preserves.

Sprinkle white chocolate chips over the pudding layer.

Garnish each serving with a fresh blackberry for presentation.

Refrigerate for at least 6 hours or overnight before serving.