Preheat the oven to 350 degrees and line a muffin tin with paper liners or grease well with oil.
Take a large bowl and combine your dry ingredients; flour, oats, pumpkin pie spice, baking soda, baking powder, brown sugar, white sugar, and salt. Stir with a whisk until combined well.
Take a medium size bowl and add all your wet ingredients; pumpkin puree, oil, apple sauce, plant milk, and vanilla extract stir until combined.
Add your wet ingredients into your dry ingredients and stir until just combined.
Take a small bowl and add ½ cup brown sugar with ½ teaspoon cinnamon.
Fill your muffin tins about ¾ full unless you want fuller muffins, then add 1 teaspoon of the brown sugar cinnamon mixture to each muffin. Then take a spoon and swirl this into the muffin.
You should have ¼ cup or so left of the brown sugar mixture if you don't, you can add more sugar, then add your remaining topping ingredients; use a fork or a pastry brush to break into small pea-size pieces. Sprinkle an even amount on the top of each muffin.
Let bake in the preheated oven for 16-20 minutes until a toothpick comes out clean, don't overbake.