Philly Cheese Steak Sliders

1. Make Italian beef by putting the roast in a crock pot. Pour the beer and packages of Italian dressing mix over top. Cook for 8 hours on low heat.
2. After 8 hours, melt 2 tablespoons butter in a medium saucepan over medium heat. Whisk in the flour and cook for 1 minute. Slowly whisk in milk, and cook, whisking constantly until thickened, about 4 to 5 minutes. Remove the mixture from the heat and whisk in the cheese until combined; season with the salt and pepper.
3. Melt the remaining butter in a sauté pan and add onions. Cook for 15–20 minutes over medium heat to caramelize. When a medium brown, add green peppers. Cook for another 10 minutes. Add mushrooms for the last five minutes.
4. Cut rolls in half lengthwise while still attached. Layer beef, veggies and cheese on the bottom of the rolls. Top with the tops of the rolls. Cut down the roll lines. Serve!