Beat eggs and sugar at low speed. Melt margarine, then add 1/2 + 1/8 cups of milk and the vanilla. Sift dry ingredients together and fold into egg and milk mixture. Mix well.
Grease and preheat 13 x 9 inch pan, then pour in mixture and bake 15-20 minutes at 375 degrees. Cool cake completely before topping.
Melt butter in small saucepan. Add brown sugar, pecans, and milk and stir until sugar is melted. Pour over cooled cake, then place cake under broiler for 4-5 minutes, watching carefully to prevent burning.