This is what I use when resting my steaks in a butter bath while I get the grill up to searing temp:
1/2 lb unsalted butter (yeah - it’s a lot, but it’s really just so that the steaks get a good soak. You can adjust.)
2 sprigs fresh thyme
2 sprigs fresh rosemary
4 cloves garlic, peeled and smashed
I melt the butter in a foil pan with all of the herbs while slow cooking the steaks, but be sure not to scorch it. If I have room on the grill, I’ll put the pan on with the steaks so that the butter gets a little smoke flavor. I cook the steaks low and indirect, so I really don’t have to worry about scorching the butter.
Once steaks reach your desired temp, place them in the pan and use the sprigs to baste them. Make sure they are coated in butter. It usually takes me about 10 minutes to get my fire roaring hot for a sear, so that’s how long I keep them in the butter. The sizzle you get when searing a butter drenched steak is a cool side effect, so if you can serve immediately off the grill, you’ll impress your guests.