Combine the flour and 1/3 cup brown sugar in a mixer. Mix in the softened butter until a dough has formed. Press into an ungreased 8x8-inch baking dish, and prick with a fork.
Bake the shortbread in the preheated oven until golden brown, about 20 minutes. While the shortbread is baking, beat the egg in a mixing bowl along with 1/3 cup brown sugar, maple syrup, and pecans. Pour the pecan mixture over the hot crust, and return to the oven. Continue baking until firmed, 12 to 15 minutes. Remove from the oven, and immediately run a knife around the edges to prevent sticking. Cool completely, then cut into 1-inch squares to serve.
