In a large bowl, cream together vegan butter, coconut sugar, and maple syrup until smooth and fluffy. This should take about 2-3 minutes with an electric mixer. Mix in pumpkin purée, flax egg and vanilla. The mixture might look a bit loose - that's totally normal!
In another bowl, whisk together oat flour, almond flour, baking soda, baking powder, spices, and salt. Make sure there are no lumps in your pumpkin pie spice. If there is, use a sifter to add it in.
Gradually stir dry ingredients into wet until a soft dough forms. Don't overmix - just until everything comes together.
Scoop cookie dough using a small cookie scoop or ice cream scoop, approximately 2 tbsp dough per cookie, roll into balls, and flatten slightly on the baking sheet. Leave about 2 inches between cookies.
Chill for 30 minutes to help prevent spreading of cookies while baking. This step is crucial for getting the right texture, so don’t skip!
Bake 9-11 minutes, until set but still soft in the middle. They should look slightly underdone - they'll continue cooking on the hot pan. Let cool completely before frosting.