For shortbread crust, preheat oven to 350F. Prepare an 8×8″ baking pan by greasing it and lining it with parchment paper.

Cream together softened butter with sugar until light and fluffy. Add in vanilla and mix until incorporated.

In a separate bowl, sift in flour. Gradually add flour to the butter mixture, mixing until just combined to avoid overworking the dough.

Press half of the dough into the prepared pan, place the remaining half of dough in the fridge.

Place pan into oven and bake for 10 minutes. The shortbread will still look somewhat underbaked, but that’s ok. Remove from the oven and allow to cool while you work on the cinnamon filling.

For cinnamon filling, in a small bowl, add melted butter, brown sugar, cinnamon, and vanilla and mix until combined.

Drop the prepared cinnamon filling by the spoonful onto the partially baked shortbread crust and spread gently into an even layer.

Roll out the remaining shortbread dough or use your hands to create flat discs about 1/4 inch thick. Place flat clusters of dough on top of the filling to loosely form a lid.

Place the pan back into the oven and bake for 20-30 minutes, until the edges are beginning to brown.

Remove from oven and cool completely.

For cinnamon icing, in a small bowl, add powdered sugar, vanilla, cinnamon, and water. Mix together with a fork until fully combined and smooth.

Pour the icing on the cooled shortbread and spread into an even layer. Allow the icing to stand on top of the bars for about 15-20 minutes to set. Cut into squares and eat!