01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish thoroughly with cooking spray or butter.
02 - Combine the strawberry cake mix, eggs, vegetable oil, and water in a large bowl. Beat with electric mixer or whisk until completely smooth and well blended, about 2 minutes. Pour batter into the prepared baking dish and spread evenly.
03 - In a separate bowl, beat the softened cream cheese and butter together until smooth and creamy, about 2-3 minutes. Add powdered sugar and vanilla extract; continue beating until fluffy and fully incorporated with no lumps.
04 - Drop rounded spoonfuls of the cream cheese mixture randomly over the surface of the cake batter, leaving some spaces visible.
05 - Run a knife or skewer through the batter and cream cheese mixture in a figure-eight or swirling motion. Do not overmix—you want distinct marbled patterns, not a homogeneous blend.
06 - Sprinkle white chocolate chips, chopped strawberries, coconut (if using), and nuts (if using) evenly across the top of the cake.
07 - Bake for 40-45 minutes until edges are golden brown and the center is set. A toothpick inserted should come out with a few moist crumbs but not wet batter. Avoid overbaking to maintain moisture.
08 - Let the cake cool in the pan for at least 30 minutes before cutting. Serve warm or at room temperature. The cake is best enjoyed the same day but can be stored covered at room temperature for up to 2 days.