Butter and flour 13x9 inch glass-baking dish.

Melt butter and unsweetened chocolate in heavy large saucepan over low heat, stirring until smooth. Remove from heat.

Mix in sugar. Mix in eggs 1 at a time, then yolk. Add vanilla and then flour and stir until just blended. Mix in chocolate chips.

Pour the batter into the prepared pan and bake until the brownie layer is cooked through, 30 to 35 minutes.

Meanwhile, make pecan pie topping:

In a medium bowl, whisk together maple syrup, brown sugar, vanilla, melted butter, and salt until smooth. Add eggs and stir until combined, then
add pecans, stirring until fully coated.

Top baked brownies with pecan topping, spreading evenly. Return to oven and bake until pecan mixture is set, 20 minutes more.

Let brownies cool completely before slicing and serving. Cool on rack. Cut into 24 pieces