Combine 113g (1/2 cup) butter and 134g (2/3 cup) granulated sugar in a large bowl and mix until the butter is soft and fluffy.
Add the remaining wet ingredients, 1 large egg, 1 tsp vanilla extract, 145 g (2/3 cup) sourdough starter discard, and mix completely.
Next, mix in 190 g (1 cup) mashed banana.
In a separate medium bowl, whisk together 209 g (1 2/3 cups) all-purpose flour, 1/2 tsp salt, 1/2 tsp baking soda, and 1 1/2 tsp baking powder.
Add 50 g (1 cup) shredded coconut and 75 g (1/2 cup) chocolate chips to the bowl, tossing to coat the chocolate and coconut with the flour mixture.
Add the dry ingredients to the banana mixture and mix until just combined.
Scoop the muffin batter into the muffin pan to the top of the muffin cups.
Sprinkle 15 g (1/4 cup) shredded coconut over the top of the muffins and place into the preheated oven.
Bake at 425 for 5 minutes and then reduce the heat to 350 degrees and bake for an additional 15 minutes.
The muffins are done when the tops are a light golden brown, the tops spring back when touched gently and a toothpick comes out clean when inserted into the middle of the muffin.
Let the muffins rest in the muffin pan for 2 minutes before removing to a wire rack to cool.
Long Fermented Method
Combine the muffin batter in the same way as the Same Day Method. However, instead of scooping the batter into muffin liners, cover the bowl and refrigerate for 8-12 hours.
The next day, preheat the oven and bake as directed above.
Notes
Nutrition information is automatically calculated, so should only be used as an approximation.