Preheat oven to 425 degrees. Prepare muffins pans by lining with 12 cupcake liners. Set aside.
Grab a large microwave-safe bowl. Break chocolate into pieces and place into bowl with butter. Microwave for 30 seconds. Stir mixture and microwave for another 30 seconds. Finish off for another 10-15 seconds. Add sugar and whisk vigorously for 1 minute to help dissolve the sugar into the chocolate. It won't be fully dissolved but it will help the process begin.
Add sour cream and vanilla and gently whisk together until combined. Add eggs and gently whisk until combined.
In a separate bowl, whisk flour, cocoa powder, cinnamon, salt, and baking soda until evenly combined. Add mixture to wet ingredients and fold together with a spatula until almost combined. Add chocolate chips and finish folding until evenly combined. Don't over mix!
Scoop batter into liners, filling all the way to the top. I used an ice cream scoop to make it easier but you can use a large spoon if you don't have one.
Add topping ingredients to a small bowl. Using a small spoon, combine together. Gently sprinkle over the top of the uncooked muffins.
Bake muffins for 5 minutes at 425 degrees then immediately turn down temperature to 350 degrees, while keeping the muffins in the oven. Bake for another 15 minutes, or until toothpick comes out clean when inserted into center muffin. Remove from oven and let cool in muffin tin for 5 minutes and then remove from muffin tin to continue cooling on a wire rack.
Serve immediately or keep stored in a storage container at room temperature for up to 3 days.