01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish thoroughly with cooking spray or butter.
02 - In a large bowl, combine strawberry cake mix, eggs, vegetable oil, and water. Beat with electric mixer or whisk until completely smooth and well blended, about 2 minutes.
03 - Pour batter into prepared baking dish and spread evenly using a spatula to create a uniform layer.
04 - In a separate medium bowl, beat softened cream cheese and butter together until smooth and creamy. Add powdered sugar and vanilla extract, continue beating until fully incorporated and fluffy.
05 - Drop spoonfuls of cream cheese mixture randomly over the surface of the cake batter, leaving some gaps.
06 - Using a knife or skewer, gently swirl the cream cheese mixture through the cake batter in a figure-8 or circular motion. Do not overmix to maintain distinct marbled patterns.
07 - Sprinkle white chocolate chips, chopped strawberries, coconut (if using), and nuts (if using) evenly across the entire surface.
08 - Bake for 40-45 minutes until edges are golden brown and center is set. A toothpick inserted should come out with a few moist crumbs but not wet batter.
09 - Allow cake to cool in pan for at least 30 minutes before serving. Serve warm or at room temperature.