Preheat the oven to 350°F. Use 1 tablespoon of butter to generously grease a small baking dish—mine is 8.5 x 6 x 2 inches. If using a standard 9 x 13-inch baking dish, reference the notes section below for adjusted ingredient quantities.
In a bowl, whisk together the eggs, milk, Dijon mustard, garlic powder, salt, and black pepper until smooth.
Add half of the torn croissants to the prepared baking dish, followed by half of the ham and half of the cheese. Top with the remaining croissant pieces and the rest of the ham, reserving the remaining cheese for the top.
Slowly pour the egg custard mixture evenly over the croissants, focusing most of it around the edges. Gently press the croissants down so the bottom layers soak up most of the custard, while the pieces on top are just lightly moistened. This keeps the inside soft and custardy while allowing the top to crisp up.
Sprinkle the remaining grated cheese evenly over the top. Bake for 35-40 minutes, or until the center is set, the top is golden, and the internal temperature reaches 165°F.
Toward the end of the baking time, melt together the remaining butter and the honey. Brush the honey butter over the top as soon as the bake comes out of the oven. Garnish with chives or green onions and serve warm!