In a medium bowl, whisk together all of the poppy seed sauce ingredients. Pour evenly over all of the sandwiches. You do not have to use all of the sauce! Just use enough to cover the tops. Let sit 10 minutes or until butter sets slightly. Cover with foil and bake at 350 degrees for 12-15 minutes or until cheese is melted. Uncover and cook for 2 additional minutes or until tops are slightly brown and crispy. Serve warm.