Cut soap into smaller pieces. Place in microwave safe bowl along with coffee grounds. Microwave for 40 seconds, stir then repeat in 10-20 second intervals until soap in fully melted.
Remove and stir until soap begins to slightly slightly thicken (add fragrance if you wish at this point and stir in). Pour into the soap mold and allow to cool fully.
Cut into slices to create bars.
Notes
Time: Takes about 10 minutes to make, but then must cool at least an hour (or more) before cutting.