Mix first 5 ingrediants, add remaining ingredients and beat well. Pour into greased Jelly Roll Pan (I usually just use a 9/13 glass cake pan). Bake at 350 deg for 15-20 minutes.
Filling:
Beat together 1 cup powdered sugar and all remaining ingredients for 5min. Add 1-3 cups more powdered sugar (a little at a time until you get the consistency you want) and beat well. Spread onto cooled cake layer. Put in freezer while you make the frosting.
Frosting:
Boil together sugar, margarine, and milk for 1 1/2 minutes. Remove from heat and add chocolate chips and vanilla. Beat until cooled and slightly thickened. Spread over filling layer and let stand until frosting cools and sets.