Preheat your oven to 350°F (175°C). Grease the 9x13 inch baking pan.

In a large mixing bowl, combine the white cake mix, eggs, water, and vegetable oil. Mix well with an electric mixer on medium speed for about 2 minutes until smooth.

Pour the cake batter into the prepared baking pan. Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and let it cool in the pan for about 10 minutes. With a toothpick or skewer, poke holes all over the top of the cake, about 1 inch apart.

In a saucepan over medium heat, combine the raspberry preserves and ¼ cup of water. Stir until melted and smooth. Pour the warm raspberry mixture over the cake, allowing it to soak into the holes.

In a separate bowl, heat the heavy cream in the microwave until warm (about 30 seconds). Add the chopped white chocolate and let it sit for a minute. Stir until completely melted and smooth. Mix in the vanilla extract.

Spread the white chocolate ganache over the top of the cake, covering it evenly. Allow the cake to cool completely at room temperature, then refrigerate for at least 1 hour to set.

Before serving, garnish with fresh raspberries if desired. Slice and enjoy!