In a bowl, stir together the melted butter, mustard, Worcestershire sauce, dried minced onion and Parmesan. Pour evenly over the sliders and sprinkle with poppy seeds.
1/2 cup salted butter, 1 tbsp yellow mustard, 1 tbsp Worcestershire sauce, 2 tbsp dried minced onion, 1/4 cup grated parmesan cheese, 2 tbsp poppy seeds