• Preheat the oven to 375℉/190℃ and line your muffin tin with 12 liners. Mash the bananas.
  1 cup ripe bananas

For the streusel

• In a small bowl, make the streusel. Combine flour, white sugar, and cold cut up butter. Using your hands, mix it together until combined into a crumbly, streusel mixture. Set aside while you make the muffin batter.
  5 tbsp butter, 1/3 cup white sugar, 3/4 cup all-purpose flour

For the muffins

• In a large bowl add in flour, cinnamon, nutmeg, salt, cornstarch, baking powder, baking soda, and salt. Using a spatula, mix until just completely combined. Set aside.
  2 1/2 cups all-purpose flour, 1 tsp baking soda, 1 1/2 tsps baking powder, 1/2 tsp salt, 2 tsps cornstarch, 2 tsps cinnamon, 1/8 tsp nutmeg
• In a large bowl, whisk mashed bananas, oil, eggs, vanilla, sour cream, and dark brown sugar. Whisk until well combined. There may be lumps from the bananas but that is okay.
  1 cup ripe bananas, 1 1/3 cup dark brown sugar, 1/2 cup oil, 2 large eggs, 3/4 cups full fat sour cream, 2 tsps vanilla
• Combine the dry ingredients with the wet until just combined using a spatula. Don't over-mix!
• Evenly divide the batter between 16 liners, they should be almost or all the way full. Using a cookie scooper helps big time to minimize the mess. Sprinkle a handful of streusel on top.
• Bake the muffins at 375℉ for 17-21 minutes. The muffins are ready when they bounce back at touch or a toothpick inserted comes out clean.
• These muffins stay fresh covered at room temperature for up to 3 days, and in an airtight container in the refrigerator for up to a week!