Preheat the oven to 350 degrees. Line a muffin tin with silicone cupcake wrappers OR parchment wrappers.
In a large bowl prepare flax egg by whisking flax and warm water together. Set aside to gel for 10 minutes.
Once thickened, whisk in mashed banana, oil, maple syrup, vanilla and sourdough discard.
Next add in dry ingredients. Switch to a spatula or a spoon to mix thoroughly.
Finally, gently fold in wild blueberries if using and scoop into muffin liners. IF USING JAM METHOD, spoon a heaping tbsp into the bottom of cups, then add 1 tsp of blueberry chia jam in the middle and top with remaining batter.
In a separate medium sized bowl mix together the crumble topping. Use your fingers to top each muffin. Place in a preheated oven and bake for 20-22 minutes or until the toothpick comes out clean. Do not overbake or they become too dry.
Once done, remove from the oven and let rest in the muffin tin on a wire rack for 10 minutes. Gently remove from tin and allow to cool completely before eating.
BLUEBERRY CHIA JAM INSTRUCTIONS
In a small pot, heat berries over medium heat. Once they start to break down mash with a spoon, fork or potato masher. Cook for about 10 minutes, decreasing heat if it starts to burn.
Add in maple syrup and cook for 5 minutes more.
Remove from heat and add in chia seeds.
Transfer to a jar and cool completely before sealing and placing in the fridge. Keeps for up to 10 days.
*Macros are provided as an estimate for convenience. Your final numbers will vary depending on ingredient brands, substitutions, and how you portion the recipe.