Pre-heat the oven to 375ºF. Prepare muffin pan by spraying the wells generously with non-stick spray, or line with muffin cups, if you prefer.
To make the topping: Combine the flour and sugar in a small bowl. Use a pastry blender to cut the butter into the flour mixture. The mixture will resemble coarse crumbs, when ready. Stir in the chopped pecans and set aside.
To make the muffins: Sift the flour, baking soda, salt, cinnamon and nutmeg into a medium bowl, mix in the granulated sugar and brown sugar.
Cut the butter into the flour mixture using a pastry blender, until it resembles coarse crumbs. Make a well in the center and set aside.
In a small bowl, whisk the egg and milk together. Mash the bananas into the milk mixture. Pour into the well of the flour mixture and stir until combined. Fold in chocolate callets/chips. The batter will appear lumpy.
Use an ice-cream scoop to add the batter to each well of the muffin pan. Use a spoon to sprinkle the topping generously over the batter.
Bake on the middle rack for 18-20 minutes, depending on your oven. Cool in pan on a wire rack for a about five minutes.
Serve warm with your favourite hot beverage!
Have a great day and I'll see you back here in a few days with some Valentine's Day treats!