
Preheat oven to 210°C / 410°F (190°C fan). Place shelf in the top ⅓ of the oven. Line a 12-hole standard muffin tin with paper cases.
Sift Dry ingredients: Sift flour, baking soda and salt into a large bowl.
Bloom cocoa: In a separate bowl, sift the cocoa then add coffee and HOT milk. Whisk until lump-free.
Add remaining Wet ingredients: To the cocoa mixture, add sugar, oil, egg, sour cream and vanilla. Whisk until smooth.
Mix flour in: Pour Wet mix into the bowl holding the flour. Whisk until smooth and glossy. Stop once it's smooth, don't mix excessively. (Note 7)
Add chocolate chips: Stir in most of the chocolate chips - reserve approx ¼ cup for topping.
Fill muffin tin: Divide the batter between the 12 holes, up to 0.5cm / 0.2" from rim of paper liner. (Note 8)
Top with chocolate chips: Top muffins with reserved chocolate chips (just pile in middle, they spread when baked).
Bake at high temp, 5 minutes: Bake for 5 minutes in preheated oven. The higher temp kick will start the rise.
Lower oven, 20 minutes: Turn oven DOWN to 190°C / 375°F (170°C fan). Bake a further 20 minutes, checking at 15 minutes. When toothpick comes out clean they're ready. Don't confuse melted chocolate with raw batter!
EAT! Rest in muffin tin for a few minutes, then transfer to cooling rack. Allow to cool for 15 minutes before devouring!