01 -
Preheat the oven to 163°C. Grease an 20×20-centimetre baking dish with nonstick spray and line with parchment paper, allowing an overhang for easy removal. Trace the base of the pan onto a separate sheet of parchment for later use.
02 -
In a medium bowl, whisk together all-purpose flour, almond flour, and kosher salt until well blended. Set aside.
03 -
In a large mixing bowl, use an electric mixer to cream powdered sugar and softened butter until light and fluffy. Add egg and vanilla extract and mix until combined. Incorporate the dry ingredients by hand until a soft dough forms.
04 -
Press half of the shortbread dough evenly into the prepared baking dish. Flatten the remaining dough onto the outlined parchment paper to match the pan size. Set both aside.
05 -
In a separate bowl, combine brown sugar, cinnamon, all-purpose flour, melted butter, and maple syrup (if using), mixing until the texture resembles damp sand.
06 -
Distribute the brown sugar cinnamon filling evenly over the shortbread base in the baking dish, gently pressing it down. Carefully flip the remaining dough from the parchment onto the filling layer and remove the paper.
07 -
Bake uncovered on the middle oven rack for 40–45 minutes, or until the edges are golden. Remove from the oven and let cool at room temperature for 30 minutes. Transfer to the refrigerator and chill for an additional hour uncovered.
08 -
In a bowl, whisk together powdered sugar, cinnamon, melted butter, maple syrup (if using), and 2 tablespoons milk. Add extra milk gradually to reach a spreadable consistency.
09 -
Spread the cinnamon icing over the chilled bars. Optionally, sprinkle with flaky sea salt. Slice into 9–12 bars as desired.