Melt butter in a saucepan until it starts to caramelize. Remove from heat and allow to cool slightly before adding to muffin batter.
In a large bowl, mash together the bananas, sugars and eggs. Add the browned butter and Greek yogurt and mix until combined.
In a separate bowl, whisk together the dry ingredients.
Slowly pour the dry ingredients into the bowl of wet ingredients, stirring as you add, until well incorporated.
Fold in the chocolate chips.
Scoop batter into a lined muffin pan, so that the cups are no more than 3/4 of the way full.
Chop the pecans in a food processor until you have fine crumbs. Use a fork to mix together the pecan crumbs with butter, flour, and brown sugar.
Scoop a generous spoonful of the crumble on top of each muffin cup.
Bake for 7 minutes at 405°F, then reduce heat to 375°F and bake for 10 more minutes.
Cool in pan for a couple minutes, then move to a wire rack to finish cooling.
Notes
Nutrition information is provided as an estimate only.Storage: Line an airtight container with paper towels and store muffins at room temp for 1–2 days or in the fridge up to 5 days.Freezing: Wrap each muffin in plastic wrap, then freeze in a bag for up to 3 months. Thaw at room temp or warm in microwave 20–30 seconds.