Preheat oven to 350 degrees; grease and flour 16x11x1 pan.
Mix the cake mix, eggs, and water for 3 minutes.
Pour batter into pan and bake for 20 minutes (make sure center is firm).
Meanwhile, melt margarine and remove from heat; let cool.
Add vanilla after margarine cools.
Add remaining "Crumbs" ingredients into large bowl.
Mix slowly adding margarine/vanilla, mixing with a fork as you do so until moist and crummy.
Pour onto cake and bake 45 minutes longer.
Cool; coat well with confectioners sugar.
