Preheat the oven to 320 degrees. Line a 9-inch baking dish with baking parchment. Cream the butter and sugar with an electric mixer until light and fluffy. Beat in the egg, then add the pancake mix and combine. Press into base of the pan and bake for 20 minutes. Immediately sprinkle the chocolate chips on top and return to the oven for 2 minutes. Use an offset spatula to smooth over the melted chocolate, then sprinkle the chopped pecans on top. Leave to cool in the tray on a baking rack until the chocolate has set, then slice into squares and serve.