Good employee quits. Do these 8 things
1. Wish them all the best
2. Offer to give them great recommendations
3. Tell them how valuable they have been to the team, and how much you appreciate them
4. Tell them you will be happy to hire them back should they want to
5. Ask them if they have any advice for you and for your management style
6. Look in the mirror as to why they resigned. Perhaps you did not give them room to grow, support when they needed you, appreciation when it was due, freedom to choose best solutions, time to listen to them
7. Continue to treat them as a highly valued employee. Just because someone found a better opportunity does not mean they are a traitor.
8. Be happy for them, they deserve it.