Preheat the oven to 350° F. Line a 9x13 inch baking dish with parchment paper.2 In a large mixing bowl, cream together the butter and brown sugar. Add the maple syrup and vanilla, beat until light and fluffy. Add the egg and mix until combined. Add the flour, baking soda, and salt, beat until combined and the dough forms a ball. If the dough feels too wet, add 2-4 tablespoons additional flour. Spread the dough out into the prepared dish. Bake for 10-12 minutes, until lightly golden on top. Meanwhile, make the pecan filling. In a mixing bowl, cream together the butter and brown sugar. Add the maple syrup, vanilla, and bourbon (if using) beat until combined. Add the eggs, one at a time, and mix until combined. Stir in the pecans and chocolate chips. Gently pour the pecan filling over the cookie crust, spreading the filling in an even layer. It will be thin. Return to the oven and bake another 20-25 minutes, until the bars are golden brown and just set in the center. They should wiggle a bit. Let cool, then cut into bars and enjoy!