Grilled Roast Beef Sandwich with Guinness Caramelized Onions

Using a microwave-safe plate or bowl, add the sliced onions and microwave until tender, about 4–5 minutes.

Coat a large nonstick pan with cooking spray. Add the cooked onions, ½ cup Guinness, and Worcestershire sauce. Simmer for about 15 minutes, stirring often, until most of the liquid has evaporated. Remove from heat and stir in the mustard.

Spread the outside of each slice of bread with ½ teaspoon reduced-fat butter. On the inside of one slice, layer half the roast beef (about 2 ounces), half the cooked onions, and half the cheese. Repeat for the second sandwich and top with the remaining bread, buttered side up.

To cook in a panini maker or electric grill: preheat the appliance, place both sandwiches inside, and grill about 4 minutes until golden and the cheese is melted.

To cook in a pan: coat a nonstick skillet with cooking spray and cook the sandwiches 2–4 minutes per side over medium heat until golden and the cheese has melted.