Preheat the oven to 400°F / 200°C. Line a muffin pan with paper liners or grease the pan with oil or butter.

Add walnuts and rolled oats to a food processor or blender (or mortle) and mix quickly into a coarse flour. Transfer to a large mixing bowl together with the rest of the dry ingredients.

Add buttermilk, oil, bananas and dates to the food processor or blender and mix until smooth, then transfer to the mixing bowl with the dry ingredients.

Crack the eggs in a separate bowl and beat them for about a minute before adding them as well. Use a spatula to carefully fold everything until combined.

Divide the batter into the muffin tins, drop a bunch of blueberries on top of each muffin and gently push them down a bit.

Mix together the granola crumble in a small bowl and add it on top of the muffins. Bake for about 18-20 minutes.

Best enjoyed still warm from the oven!