Directions

1. First, make the blue cheese butter by combining the softened butter in a food processor with the remaining ingredients. Pulse the mixture until it’s combined. Transfer the mixture to a piece of plastic wrap, fold it into a log form, secure the edges and place it inside the freezer until it’s hardened.
2. Then, make the steak filling by combining 2 tablespoons of the blue cheese butter with the sliced onions in a large skillet over medium-low heat. Sprinkle with 1/8 teaspoon of salt and 1/8 teaspoon of pepper. Toss while cooking, allowing the onions to caramelize, about 10–15 minutes. Then, increase the heat to medium high, add the steak, 1 more teaspoon of salt and ½ teaspoon of pepper to the tossed onions. Drizzle in the Worcestershire sauce along with 2 more tablespoons of the blue cheese butter. Toss ingredients together and reduce the heat to low until ready to serve.
3. Before constructing the sandwiches, toast the bread with any remaining blue cheese butter. Top with additional blue cheese crumbles.