Preheat your oven to 350°F (175°C). Grease your loaf pan with butter or non-stick spray, ensuring it’s well-coated to prevent sticking.
In a small bowl, combine the instant coffee powder and hot water. Stir until the coffee is dissolved, and set aside to cool slightly.
In a large mixing bowl, beat the softened butter and granulated sugar together using an electric mixer on medium speed until light and fluffy, about 3-5 minutes.
Add the eggs, one at a time, mixing well after each addition. Then, add in the vanilla extract and the cooled coffee mixture. Mix until well combined.
In another bowl, whisk together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt until evenly mixed.
Gradually add the dry ingredient mixture to the butter mixture, alternating with the sour cream. Begin and end with the dry ingredients, mixing just until combined. Be careful not to overmix!
Gently fold in the mini chocolate chips using a spatula, ensuring they are evenly distributed throughout the batter.
Pour the batter into the prepared loaf pan, smoothing the top with a spatula. Bake in the preheated oven for 60-70 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 minutes. Then, transfer it to a cooling rack to cool completely.
If you wish to add a glaze, whisk together the powdered sugar, cocoa powder, milk, and vanilla extract until smooth. Drizzle over the cooled cake and top with chocolate shavings.
