Preheat oven to 200C.
Line muffin tins with muffin liners.
In a large mixing bowl, sift cocoa powder, baking powder, baking soda, salt, cinnamon, and flour together.
Then combine in buttermilk, melted butter, vanilla extract, and eggs in a bowl or measuring cup.
Give it a good whisk.
Add the wet ingredients into the dry ingredients.
Mix until almost combined, then add chocolate chips.
Fold it in about 4 times. Do not over mix!
Divide batter into liner, and top with crumble mix.
Bake 15-18 minute