Preheat the oven to 400°F (200°C). Place the 12 paper liners in a muffin pan.
Dissolve the instant coffee into the milk and set aside. Melt the butter. Beat the eggs in a small bowl.
Place sifted flour, sugar, baking powder, cinnamon and salt into a large bowl.
Add melted butter, milk and eggs to the flour mixture and mix to combine. Do not overmix, some small lumps in the batter are ok.
Fold half of the chocolate chips into the batter.
Distribute the batter evenly among the muffin liners and sprinkle the remaining chocolate chips on top.
Bake on the middle rack of the oven for about 20 minutes. Remove the muffins from the pan and let them cool on a wire rack.
Notes
Espresso Amount: Feel free to adjust the espresso powder according to your coffee preference. More for a bold coffee flavor, less for a subtle hint.
Mixing: Don't overdo it with the mixing. A few lumps in the batter are fine.
Storage: Enjoy these muffins fresh for the best taste or store them in an airtight container at room temperature for up to 3 days. For longer storage, freeze them in a sealed container for up to a month.