Instructions

1. Preheat oven to 350F. Line a standard muffin tin with muffin liners.
2. In a small saucepan, brown the 1/2 cup unsalted butter. Remove from the heat and pour into a large mixing bowl to cool.
3. In a medium sized mixing bowl, combine the flour, baking soda, and salt. Whisk well to combine, and set aside.
4. To the brown butter, add the sugar. Add the 1 egg to a liquid measuring cup and then add milk to make one cup. Add this to the mixing bowl with the butter and sugar. Whisk well. Then add the 1 ripe banana, mashed with a fork, and whisk until everything is well combined.
5. Finally, fold in the flour mixture, stopping when there are still a few streaks of dry flour left.
6. Prepare the streusel: whisk together the flour, sugar, muesli, and salt. Work in the butter, mixing until coarse crumbs form. Sprinkle over the muffins.
7. Pour the batter into the prepared muffin tin, and sprinkle the tops with the streusel mixture. Bake for about 25-30 minutes, until the muffins are risen and golden brown on top, and a toothpick inserted in the middle comes out clean.
8. You can also make this in a loaf pan by baking for 45-60 minutes.
9. Let cool in the pan before removing.