Preheat oven to 400°F (204°C)
Line muffin tin with muffin liners or grease generously. Set aside.
Create a blend of chai spices by combining your cinnamon, cardamom, ginger, clove, anise, and nutmeg.
Whisk the flour, baking powder, baking soda, chai spice blend, and salt together in a large bowl. Set aside.
In a seperate bowl, whisk the melted butter, bananas, honey, sugar, and eggs together until combined. Then whisk in the sour cream, and milk.
Pour wet ingredients into dry ingredients and fold together with a rubber spatula or wooden spoon until thoroughly combined. Use a whisk to rid any large lumps of flour, if needed. Avoid overmixing. The batter will be thick.
Divide batter between each prepared muffin cup, filling almost all the way to the top, setting aside just enough room for crumble on top. Set aside and make crumble topping.
In a large, microwave-safe bowl, melt the butter, for about 1 minute on high power. Add the sugar into the melted butter and whisk to combine. Add the flour, optional salt, and stir to combine, gently. You want mixture to be crumbly, not formed into a dough. Add crumble to the tops of your muffin batter.
Bake at 400°F for 15-18 minutes, or until the crumble tops are lightly golden brown and centers are set. Stick a toothpick in the center of a muffin to test for doneness. If it comes out clean, the muffins are done. If not, continue baking for an additional 4-5 minutes and test again.