Mix all ingredients except chocolate chips with and electric mixer till well combined.
Fold in the chocolate chips.
Pour into greased 10x15 inch baking pan.
Bake at 350 degrees for 25 minutes or until toothpick comes out clean.
Beat the butter with electric mixer.
Add powdered sugar and beat.
Add strawberries and vanilla.
If needed to make the icing spreadable, add a bit of milk a teaspoon at a time.
Spread icing on cake.
Store in the refrigerator.