In a medium bowl, combine cabbage, mayo, jalapeño peppers, cilantro, lime juice, sugar, cayenne pepper and salt. Mix well and set aside.
Warm a skillet over medium heat for 3 to 5 minutes. Place the bread slices on a flat work surface. Spread 1 tablespoon of butter evenly over one side of each slice of bread.
Place two of the bread slices onto the hot skillet, butter side down. Top each with 1/2 cup shredded Wisconsin cheddar cheese. Cook for 3 to 4 minutes, or until the cheese begins to melt around the edges.
Using a spatula, move the bread from the skillet back to the work surface. Top one of the slices with the roast beef, spicy slaw, bacon, barbecue sauce and the other cheesy slice of bread, cheese side down. Serve immediately and serve any extra slaw as a side!