Heat the oven according to the blondie mix directions. Coat an 8-inch baking dish with nonstick spray or line with parchment paper.
Prepare the blondie batter as directed on the box, then fold in the toffee pieces and chopped pecans until just combined.
Spread the batter evenly in the pan. Scatter a handful of fall leaf sprinkles across the top and gently press in a few royal icing accents.
Follow the baking time on the package. Once done, let the blondies cool completely in the pan.
Whisk up the maple glaze included in the mix. Drizzle it generously over the cooled blondies, leaving the royal icing characters peeking through. Add a final sprinkle of leaves for extra color.
Allow the glaze to firm up for about 30 minutes before slicing into squares. Plate, serve, and enjoy your autumn-ready blondies!