Line a small square container or baking dish with parchment paper.
Add the sweetened condensed milk, chocolate chips, and butter to a microwave-safe bowl.
Microwave for 30 seconds, stir, then continue microwaving in 15-second intervals until fully melted and smooth.
Stir in the instant coffee until completely dissolved.
Mix until the fudge becomes glossy and thick.
Pour the mixture into the prepared container and smooth the top with a spatula.
Refrigerate for 45 minutes, or until firm enough to cut.
Remove from the container and cut into 25 small squares.
