Here’s how you can make these espresso brownie bites step-by-step:

1. Preheat the oven and prepare your pan
   Start by preheating your oven to 350°F (175°C). Line a mini muffin tin with paper liners or grease it with cooking spray to ensure that your brownie bites come out easily once baked.
2. Melt the butter
   In a microwave-safe bowl, melt the butter in the microwave for about 30 seconds or until fully melted. Set it aside to cool slightly.
3. Mix the wet ingredients
   In a large bowl, whisk together the melted butter and sugar. Add the eggs and vanilla extract, and whisk until smooth and well-combined. This is where the magic happens—the sugar and butter will create a rich, glossy base for your brownies.
4. Dissolve the espresso powder
   In a small bowl, dissolve the instant espresso powder in a tablespoon of hot water. Stir it well so that the espresso is completely dissolved. Add this mixture to the wet ingredients and mix it in thoroughly. This will ensure that the coffee flavor is evenly distributed throughout the batter.
5. Combine the dry ingredients
   In a separate bowl, whisk together the flour, cocoa powder, and salt. This step helps distribute the dry ingredients evenly, ensuring there are no lumps in your batter.
6. Mix the wet and dry ingredients
   Gradually add the dry ingredients to the wet ingredients, stirring gently until combined. Be careful not to overmix—the key to fudgy brownies is mixing just until everything is incorporated. The batter will be thick and slightly glossy.
7. Fold in the chocolate chips
   Gently fold in the semi-sweet chocolate chips. These will melt into the brownie bites as they bake, creating gooey pockets of melted chocolate.
8. Fill the muffin tin
   Spoon the batter into the mini muffin tin, filling each cup almost to the top. You want these brownie bites to be generous and indulgent!
9. Bake and check for doneness
   Bake the brownie bites for 15-20 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs (not wet batter). Every oven is different, so start checking around the 15-minute mark to avoid overbaking.
10. Cool and enjoy!
    Let the brownie bites cool in the tin for a few minutes before transferring them to a wire rack to cool completely. These brownie bites are best enjoyed once they’ve cooled enough to set, but if you can’t wait, I won’t judge you for digging in early!