Preheat the oven to 350 degrees and lightly spray a Madeleine pan with cooking spray. Mix the oat milk and apple cider vinegar together and let sit for 5 minutes to turn into “buttermilk.”
Sift the flour, sugar, baking powder, baking soda, salt and spices together in a mixing bowl. Add the canola oil, pumpkin puree and vanilla extract to the oat milk mixture and stir until combined.
Slowly pour the wet ingredients into the dry ingredients and stir just until combined. Do not overmix.
Spoon about 1 tablespoon of the batter into each well of the Madeleine pan. Bake for 10-12 minutes or until a toothpick comes out clean and they are set in the middle. While they are still warm, gently lift the cookies out and coat them with cinnamon sugar.