1/4 cup unsalted butter, softened
1 cup packedlight brown sugar
1 egg
1 1/4 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon cream of tartar
2 teaspoons vanilla extract
4 cups chopped pecans
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch pan. Stir together white sugar, brown sugar and egg.
Arrange pecans in the bottom of the 9x13 inch pan. Rub lightly with a fork on all sides.
In a large bowl, sift together the flour, baking soda, cream of tartar, and vanilla. Set aside.
In a medium bowl, mix pecans, brown sugar, rum chocolate chips, butter, pecans and sugar. Beat well.
Spread the pecans evenly over the top of the cake. Spread remaining sugar syrup and pecans over the cake swirl, taking care not to break pecans. Crumble pecans over cake.
Bake in the preheated oven for 50 minutes, or until center of the cake springs back when withdrawn from the pan. Cool and frost frost.