Add oat flour, salt, baking powder, cacao powder to a bowl and mix to combine.
Add oil, maple syrup to the dry ingredients and mix everything to form a dough. Use hands if needed, make sure dough is well mixed.
Place the dough in the refrigerator for 10 mins, this step helps to handle the dough while making cookies ( if not dough might be sticky ).
Take 2 tbsp of dough and make a round ball. Press dough ball to form a disc. Place 1 tsp of frozen Nutella in between the disc and cover it to form a ball ( by this step you should have a round dough filled with frozen Nutella in the center ). Place in between hands and press with light pressure to get a round cookie shape.
Repeat till all the dough is finished.
Place cookies on a parchment-lined baking tray and bake at 350F for 10 mins.
Let them cool to handle and drizzle melted chocolate on top if desired!
Notes
Storage: Can store in an air-tight container on counter-top for up to 3-4 days or in the refrigerator for up to a week.