Sift cake mix into bowl. Add sour cream, whole milk, eggs and jello/milk mixture. Mix well. Fold in strawberries. Pour batter into greased/floured pan(s) and bake at 325 degrees for approximately 40 minutes or until toothpick inserted into the center comes out cleanly. Frost with buttercream frosting.
Optional: If 2 layer pans are used fill with 1/4 cup strawberry pastry filling (available at cake decorating shops) mixed with buttercream frosting.
Another option would be to fold 1/4 cup thawed* frozen strawberries into the regular buttercream frosting recipe for a Strawberry buttercream frosting reducing the amount of cream/milk from 1/2 to 1/4 cup.