When/If you feel gratitude towards your therapist for their work with you do you ever express it in any way? If so, how? And how frequently?

I think I had embarrassed mine by telling them how I appreciated the way they had helped me through a difficult session. They turned red and suddenly they were the one who found eye contact difficult. Usually they are rather composed so it was surprising to see them became bashful... especially to that degree. Since that time I've been hesitant to offer such sincere gratitude again. It had left me with the sense that while they were grateful for what I said, they were bothered by their loss of ability to maintain their professional mask.

I don't want to make my therapist uncomfortable, but neither do I want to behave like I don't recognize their difficult and emotionally draining work. I'm curious how you all handle it.