Preheat your oven to 350℉ (175°C).
In a large mixing bowl, combine the oat flour and cinnamon.
Add the egg and pumpkin puree to the dry ingredients.
Use a handheld mixer to blend the mixture until it forms tiny clumps.
Shape the dough into a ball, wrap it in plastic wrap or cover with a clean cloth, and chill it in the fridge for 15-20 minutes.
Once chilled, roll out the dough with a rolling pin and cut out treats using cookie cutters.
Place the treats on a baking sheet lined with parchment paper (optional) and bake for 20 minutes.
Transfer the baked treats to a cooling rack.
Optional Icing: Mix cornstarch with water until thick. Drizzle over the cooled treats if desired.
Add a pinch of cinnamon on top of all the treats.
