Method (streusel)

1. In a medium-sized bowl, stir together the flour, sugars and cinnamon.
2. Add in the room temperature butter and use a fork to mix and claw the ingredients together until combined but still clumpy. Don’t over-mix or the streusel will become like a soft paste, simply toss together until mixture is clumpy, no longer dry, and the flour is completely combined. Set aside while you make the banana muffin mixture. Make the streusel the day before and store in the fridge in a sealed container.

Method (banana muffins)

1. Line 2 cupcake tins with cupcake / muffin liners.
2. In a bowl, mash up the ripe banana until soft and runny and pour in the milk, oil and apple cider vinegar. Stir to combine, set aside.
3. In a separate bowl, sift together the flour, sugars, cinnamon, baking powder and bicarbonate of soda. Whisk to combine.
4. Pour the wet in to the dry ingredients and fold everything together until just combined. Don’t over mix!
5. Rest the muffin batter. Cover the bowl with grease proof paper or a tea towel and place into the fridge to rest for at least 1 hour or overnight.
6. When ready to bake the muffins, preheat the oven to  180°C fan.
7. Fill each muffin / cupcake case to the very top of the liners with the muffin batter. It makes it easier if you use an ice-cream scoop to scoop the batter into the cases, alternatively use spoons. Top each muffin with a good portion of the streusel (make sure the streusel is overing the batter.)
8. Place into the middle of the oven and bake for 25-30 minutes minutes at 180°C fan. You’ll know the muffins are ready until the skewer / toothpick inserted into the middle of the muffins come out clean. 
9. Remove the muffins from the oven and allow to cool on a wire rack before frosting. They will be very hot so allow them to cool fully before tucking in.