Method
1. Pre-heat oven - 175°C
2. Grease a clean mini doughnut pan
3. Add all purpose flour, baking powder, baking soda, salt, nutmeg and ground cinnamon to a clean medium bowl
4. Whisk briefly then set aside
5. Add unsalted butter to a clean small glass bowl
6. Melt in microwave - low heat
7. Mix in vanilla extract to the small glass bowl
8. Get a clean stand mixer bowl
9. Transfer butter to stand mixer bowl
10. Add granulated sugar, buttermilk, greek yogurt and egg to the batter
11. Beat until smooth - paddle attachment
12. Add banana to the batter
13. Mix until well combined
14. Transfer dry ingredients to batter
15. Mix until combined
16. Transfer batter to mini doughnut pan
17. Bake until lightly browned - 10 min
18. Transfer onto cooling rack
19. Add unsalted butter to a clean saucepan
20. Heat gently until lightly browned - medium heat
21. Add powdered sugar to a clean large mixing bowl
22. Add vanilla extract and heavy cream to the frosting
23. Transfer content of saucepan to frosting
24. Whisk until smooth
25. Dip content of mini doughnut pan into frosting
26. Sprinkle with walnuts