Preheat your oven to 190℃ (375℉) for a conventional oven (refer to note 2 for convection oven settings). Line a 12-cup standard muffin tin with paper liners. This recipe yields approximately 15 muffins, so prepare a second tin with a few liners or see note 3 if only one tray is available.

In a medium-sized mixing bowl, sift together the flour, baking soda, baking powder, and salt. Stir with a whisk or fork to ensure even distribution of the dry ingredients, then set aside.

In a large bowl, combine the cocoa powder, instant coffee powder, and hot water. Whisk these ingredients until they form a smooth, lump-free mixture.

To this mixture, add the light brown sugar, vegetable oil, vanilla extract, sour cream, and egg. Whisk thoroughly until the mixture is well blended and silky.

Gradually incorporate the sifted dry ingredients into the wet mixture. Use a whisk initially to combine the ingredients, but avoid overmixing. Switch to a spatula to scrape down the sides and ensure the batter is evenly mixed.

Fold in about 1½ cups of chocolate chips, reserving roughly 1/3 cup for topping. Use the spatula to gently mix the batter until the chips are evenly distributed. Take care not to overmix, as this could affect the muffin texture.

Spoon the batter into the prepared muffin liners, filling each about three-quarters full. Avoid overfilling to prevent the muffins from spilling over as they bake. Sprinkle the reserved chocolate chips evenly over the tops of the muffins.

Bake for 20-25 minutes, checking for doneness at the 20-minute mark. Insert a toothpick into the center of a muffin – it should come out mostly clean, with only a few moist crumbs. If necessary, bake for a few minutes longer.

Once baked, allow the muffins to cool in the tin for 10 minutes before transferring them to a wire rack. Let them cool completely for an additional 15-20 minutes before serving. Enjoy the rich, chocolatey goodness!