Muffin Preparation

• Mash the bananas until mostly smooth with some small chunks remaining. Measure out all dry ingredients and whisk together in a medium bowl. Prepare the streusel topping by combining the flour, brown sugar, cinnamon, and salt in a separate bowl. Cut the cold butter into cubes and work it into coarse crumbs. Preheat the oven to 425°F.
• In a large bowl, combine the mashed bananas, vegetable oil, eggs, and vanilla. Whisk vigorously for about 1 minute until well combined and slightly emulsified.
• Pour the dry ingredient mixture into the wet mixture. Fold everything together with as few strokes as possible, then fold in the chocolate chips and let the batter rest for 15 minutes.
• Place paper liners in every other hole of a standard 12-cup muffin pan. Divide the batter among the lined cups, filling each about three-quarters full. Top each muffin with streusel mixture and extra chocolate chips.
• Bake at 425°F for 7 minutes. Then lower the oven temperature to 350°F and bake for 16-18 minutes longer, until a toothpick comes out with a few moist crumbs. Let muffins cool in the pan for 5 minutes before transferring to a wire rack.
• Let the muffins cool for at least 20 minutes before serving. Muffins are best eaten the same day but will keep in an airtight container for 2-3 days.