Chocolate Peanut Butter Crunch Cake

CRUMBS
1 1/2 c Unbleached flour
1 c Brown sugar — packed
1 Stick margarine — softened
1/2 c Peanut butter

-CAKE
2 Egg whites — whipped
1/2 c Skim milk — at room
Temperature
1 ts Vanilla
1/2 ts Baking powder
1/2 ts Baking soda

Preheat oven to 350. Prepare a 8″ square baking pan with cooking
spray and flour. To prepare chocolate peanut butter swirl, melt the
chocolate chips and peanut butter in a small saucepan over low heat,
stirring often until smooth. Remove from the heat; let cool while
preparing the crumbs and batter. To prepare crumbs, combine the
flour, brown sugar, margarine, and peanut butter in a mixing bowl
until the mixture forms crumbs. Remove 3/4 cup (tightly packed) of
the mixture and set aside. To prepare cake, add egg whites, milk,
vanilla, baking powder, and baking soda to the remaining crumbs in
the mixing bowl until thoroughly moistened. Spread half of the
batter in the prepared pan; gently streak half of the chocolate
peanut butter mixture over the top. Repeat with the remaining batter
and chocolate peanut butter mixture. Scatter the reserved crumbs
over the top, pressing them in gently so they adhere to the batter.
Bake for about 50 minutes or until crumbs and top of the cake are
firm. Cover the pan loosely with aluminum foil, if the cake is
getting too dark during baking, loosely cover it with a piece of
aluminum foil. Let the cake cool in the pan on a wire rack for 15
minutes. Loosen around the sides of the pan, then carefully invert
onto the rack and turn right-side-up. Cool completely before serving.