01 - Preheat a large nonstick skillet or griddle over medium heat.
02 - In a small bowl, whisk together the honey mustard and mayonnaise until smooth and well combined.
03 - Open each Hawaiian roll and spread a thin layer of the honey mustard mixture on the inside of both halves. Place a half slice of cheddar cheese on the bottom half of each roll. Top with half a slice of ham if using, then cover with the top half of the roll.
04 - Spread the softened butter evenly on the outside tops and bottoms of each assembled roll.
05 - Place the mini sandwiches in the skillet, pressing lightly with a spatula. Grill for 2 to 3 minutes per side until the bread is golden brown and the cheese has melted completely.
06 - Remove from heat and sprinkle with poppy seeds and chives immediately if desired. Serve warm while the cheese is still melted.