Preheat the oven to 375 degrees. Prepare a baking sheet with parchment paper and set aside.
In a small bowl, add butter, brown sugar, honey, dijon, poppy seeds, and garlic powder. Microwave for 30 seconds until the butter is mostly melted, and whisk until smooth.
Cut the croissants in half horizontally, and place the bottom half of each croissant on a baking sheet. Top each croissant with half a slice of cheese and ham. To the top half of the croissant, spread lightly with pesto.
After all 16 are assembled, use a pastry brush to brush the butter mix all over the top of the croissants.
Bake for 15-17 mins until the croissants are golden and toasted. The cheese will be nice and melty!
Assemble the ham sandwiches on a platter and sprinkle lightly with finely chopped green onions.