Florence Goddard's Thin Cake

1/2 cup butter
1/2 cup margarine
1 cup brown sugar (packed)
1 egg yolk
2 cups flour
1 tsp. vanilla
1 pkg. semi-sweet chocolate chips
1/2 cup chopped nuts

Cream together the sugar and butter and margarine. (The original recipe card says "shortening", but I assume this means the butter and margarine.)
Add the egg yolk and mix well.
Add the flour and mix well.
Add the vanilla and...you guessed it!...mix well!
Spread this batter thinly on a cookie sheet.
Bake for 10 minutes at 350°.
Reduce heat to 300° and cook 5 minutes longer, or until brown.
(ED: I can't imagine that reducing the oven temp from 350° to 300° would make any difference. I am guessing my oven would only lose about 5 degrees of heat in the extra 5 minutes. But who knows?)
While the cake is baking, melt the chocolate chips.
Once cake is done, spread melted chocolate chips over the top.
Sprinkle with nuts.
Cut in strips while still warm.
(ED: Does anyone else think this is just a deconstructed chocolate chip cookie?)