Preheat oven to 350 degrees F (174 C) and lightly grease a standard size muffin tin (will make 9-10 muffins as original recipe is written // adjust if altering batch size). Dust with gluten free flour and shake out excess.
Prepare flax egg in a large mixing bowl. Let set for 5 minutes.
Add banana and mash, leaving just a bit of texture.
Add pumpkin purée, muscovado sugar, maple syrup, olive oil, and vanilla extract and whisk for one minute.
Stir in baking soda, salt, cinnamon, and pumpkin pie spice, and mix. Add water and whisk once more.
Add almond meal, gluten-free oats, and gluten-free flour blend and stir until just combined. The batter should be thick and scoopable.
Divide batter evenly among 9-10 muffin tins (amount as original recipe is written // adjust if altering batch size), filling all the way full (I like big muffins!).
Quickly rinse your mixing bowl and then add crumble ingredients. Mash ingredients together with a fork or your hands until crumbly like wet sand. Generously top muffins with streusel.
Bake for 27-32 minutes or until tops are golden brown and a toothpick or knife comes out completely clean. It’s better to slightly over-bake these than under-bake because the gluten-free flour blend takes longer to cook all the way through.
Let cool for 5 minutes in the muffin tin, then gently remove and cool completely on a cooling rack. Enjoy warm or at room temperature.
Once completely cooled, store in a covered container at room temp for 3-4 days, though best when fresh. Freeze for longer term storage.
*If you're unfamiliar with muscovado sugar, read more about it here! You can also just sub organic brown sugar or coconut sugar (brown sugar being the best alternative). *If you don’t have pumpkin pie spice, use this DIY blend: 2 tsp ground cinnamon, 2 tsp ground ginger, 1 tsp ground nutmeg, 1/2 tsp ground cloves. *Nutrition information is a rough estimate calculated with crumb topping. *Recipe adapted from my 1-Bowl Vegan Pumpkin Bread and my Vegan Banana Crumb Muffins.