Preheat oven to 350°F and grease a 10" x 15" jelly roll pan.
Using a food processor or blender, puree strawberries to get about 2 cups of puree. Set aside 1/2 cup of puree.
Mix all cake ingredients together and bake according to the directions on the box. Check around 25 - 30 minutes with a toothpick or cake tester and adjust time as needed.
Allow cake to cool before frosting.
Frosting
Beat cream cheese and butter until smooth.
Mix in puree and powdered sugar and beat until smooth. Frost a cool cake and refrigerate until serving.