Preheat the oven to 350 degrees F (180 degrees C).
Arrange half of the crackers, flat-side up, in a single layer on a large rimmed baking sheet lined with parchment paper. Top each cracker with a quartered slice of cheese and a piece of bacon. Top with an additional quartered slice of cheese and remaining crackers, flat-side down.
Bake in the preheated oven until cheese is melted and bubbly, 8 to 10 minutes. Let cool 5 minutes.
Meanwhile, stir together melted butter, scallions, Dijon, salt, and garlic powder in a medium bowl. Top each cooled cracker evenly with about 1/4 teaspoon butter mixture. Serve with sour cream, if desired. Recipe developed by Isabelle Easter