Prepare crust by cutting margarine into flour, baking powder, salt and sugar until crumbly. Add beaten egg and extract. Take out approximately 1/4 cup crumb mixture and set aside for topping.
Press remaining crumbs into a lightly greased 8 inch square pan.
Combine second layer ingredients except for extract and nuts in saucepan and melt until smooth. Add nuts and extract. Spread filling over cookie base and spread remaining 1/4 cup of crumb mixture on top.
Bake at 375 oven for 25 minutes. Cool. Cut in bars.
Flavor is greatly improved if allowed to sit for a day. Store in sealed container.