Preheat the oven to 375°F (190°C) and add muffin liners to 9 cups in a standard 12-cup muffin tin.
Add the rolled oats to a food processor or dry-ingredient safe blender and mix until they turn into a coarse flour.
1 cup gluten-free rolled oats
Add the ground oats, almond flour, oat flour, arrowroot, baking powder, salt, and spices in a bowl. Stir to combine.
1 cup almond flour, ⅔ cup gluten-free oat flour, 2 tablespoons arrowroot powder, 1 teaspoon pumpkin spice, ¾ teaspoon baking powder, ½ teaspoon sea salt
In a separate bowl combine the pumpkin, oil, lemon juice, sugar, milk and vanilla, stirring well.
1 ½ cups pumpkin puree, ⅓ cup olive oil, 1 teaspoon lemon juice or apple cider vinegar, ¼ cup non-dairy milk, 1 teaspoon vanilla extract, ¾ cup coconut sugar
Add the pumpkin mixture to the dry ingredients and stir until just combined.
Make the crumble topping by mixing all of the crumble ingredients in another mixing bowl until well combined.
3 tablespoons coconut sugar, 3 tablespoons oat flour, 2 tablespoons roughly chopped pecans, 2 teaspoons olive oil, 1 pinch pumpkin spice or cinnamon, 1 pinch sea salt
Divide batter amongst 9 lined muffin cups and sprinkle the tops with a little bit of crumble on each muffin. Bake for about 25 minutes, or until the tops spring back when lightly touched.
Cool the muffins on a wire rack. Store in a sealed container at room temperature for up to three days.