Melt the butter in a skillet over medium-high heat. Add ham, garlic, onion powder, mustard, and lemon juice. Stir and cook until the edges of the ham are just beginning to brown, about 5-7 minutes.
Unroll the crescent rolls and separate. On each one, evenly distribute the cheeses, ham, and thyme - in that order.
Beginning with the thick side of the crescent triangle, carefully roll up the dough and place on a sheet pan lined with parchment paper.