Combine the flour and brown sugar in a mixer. Beat in the butter until well combined. The mixture will be quite crumbly. Press into the bottom of an ungreased 8x8 baking dish. Prick all over with a fork.
Bake until the shortbread is browned, about 20 minutes.
While the shortbread is baking, beat the egg, brown sugar, and maple syrup until well combined. Stir in the nuts. Pour the pecan mixture over the hot shortbread crust and return to the oven. Bake for 12 to 15 minutes or until the pecan mixture has firmed up.
Remove from the oven and immediately run a knife around the edges to prevent it from sticking to the sides of the dish. Cool completely before cutting.