Preheat the oven to 350 degrees F. Spray a 9-x-5-inch or a 8.5-x-4.5-x-2.5-inch loaf pan with nonstick cooking spray.
Combine the cake mix, egg whites, oil and 1 cup water in a bowl using an electric mixer, mixing until smooth. Divide the batter evenly among 3 bowls. Leave the first bowl plain. To the second bowl, add the cocoa powder and mix well. To the third bowl, add the freeze-dried strawberries and food coloring to achieve your desired color.
Using an ice cream scoop, place 2 scoops of chocolate mix into the loaf pan in different areas. Follow with 2 scoops of strawberry mix and 2 scoops of vanilla. Repeat until all the batter is used and the cake has a marbled appearance. Place in the oven and bake until a tester comes out clean, 40 to 45 minutes.
While the cake bakes, make the ganache. Heat the cream in a small saucepan over a low heat until just simmering. Place the chocolate chips in a heatproof bowl, then pour the cream over the chips and let sit for 1 minute. Whisk until smooth.
Remove the cake from the oven and let cool for 5 minutes in the pan, then remove to a wire rack (not inverted) and let cool.
Pour the ganache over the cake, letting any excess drip down the sides.