Preheat the oven to 350F and line a muffin tin with liners.
In a small bowl, combine flour, baking soda, baking powder, salt, cinnamon, and nutmeg, Whisk to combine. Set aside.
In a separate small bowl, mash 1 banana with a fork until clumpy, but not pureed. Set aside.
In a bowl of a standing mixer, combine 1/3 cup honey/maple syrup and 1 banana. (Tip: You need 1/3 cup of sweetener total, so to save on dishes, I fill a 1/3 measuring cup halfway with honey and then top it off with maple syrup.) Using the whisk attachment, turn the mixer on medium-low and set the timer for 3 minutes. The mixture should be very smooth and very well combined when the timer goes off.
Add the melted butter, Greek yogurt, egg, and vanilla and mix well, scraping down the sides of the bowl if needed.
Fold in the mashed banana and dry ingredients with a spatula until JUST combined.
Divide the batter evenly between 12 muffin tins. Each muffin tin should be about halfway full with about 2 heaping Tbsp of batter each. Gently tap the muffin tin on the counter to pop any air bubbles.
Sprinkle the pecans evenly over the muffins. Set aside.
In either of the bowls you previously used, combine the granulated sugar, brown sugar, cinnamon, and melted butter for the crumb topping. Mix together using a fork OR the whisk from the batter.
Using your fingers, pinch off some crumb topping and break it apart over the muffins.
Bake the muffins for 18-20 minutes, or until a toothpick entered in the center comes out clean.
Best served warm but keep well for a couple of days in a container with a lid.