FIRST LAYER:

4 oz. semi-sweet chocolate, coarsely chopped
3/4 c. sugar
1/2 c. unsalted butter, softened
2 lg. eggs
2 tsp. pure vanilla extract
1/2 c. flour
1/8 tsp. salt

SECOND LAYER:

1/4 c. unsalted butter
3/4 c. light brown sugar, packed
2 tbsp. flour
2 eggs, lightly beaten
3 c. pecan halves
2 tsp. pure vanilla extract

THIRD LAYER:

4 oz. semi-sweet chocolate, coarsely chopped
1/2 c. unsalted butter

Line a 9 inch square pan with aluminum foil and butter the foil. For the first layer, melt chocolate in top of double boiler. Cool slightly. Cream butter and sugar until smooth. Add eggs, mixing well after each one. Add chocolate and vanilla and mix well; fold in flour and salt. Transfer batter to prepared pan, spreading evenly. Place pan in freezer while you prepare the next layer. Heat oven to 325 degrees.

For the second layer, melt butter in small pan. Add the brown sugar and cook over low heat until smooth. Stir in flour and cook 30 seconds longer. Remove from heat and cool slightly. When mixture has cooled a bit, take a small spoonful and stir into beaten eggs. Then, whisking as you go, add egg mixture to rest of brown sugar mixture. Add pecans and vanilla and mix well. Pour pecan layer over chilled chocolate layer. Bake until a toothpick is almost clean, about 45 minutes. Transfer to a wire rack and cool completely.

For the third layer, melt chocolate and butter, whisking so the butter is completely mixed into chocolate. Pour over cooled bars, tipping pan so the entire surface is evenly coated. Refrigerate at least 2 hours before serving. Cut into small squares.