Preheat Oven: Begin by preheating your oven to 350°F (175°C).
Prepare Crackers: Arrange half of the Ritz crackers in a 9x13-inch baking dish, ensuring they are placed flat side down.
Add Ham: Tear the slices of deli ham into small strips. Fold each strip and place it onto each cracker.
Add Cheese: Cut the Swiss cheese slices into 1-inch pieces. Place one piece of cheese on top of the ham on each cracker. Top each with another cracker to form mini sandwiches.
Prepare Butter Mixture: In a small bowl, combine the melted butter with Dijon mustard, Worcestershire sauce, and garlic powder. Mix thoroughly.
Pour Butter Mixture: Evenly pour the butter mixture over the prepared cracker sandwiches in the baking dish.
Add Toppings: Sprinkle the poppy seeds and dried minced onion evenly over the top of the cracker sandwiches.
Bake: Place the baking dish in the preheated oven and bake for 10-12 minutes, or until the cheese has melted and the tops of the crackers are golden brown.
Serve: Remove from the oven and serve warm. Enjoy your delicious and buttery mini sandwiches!