Step 1

Combine onion, Worcestershire, paprika, garlic powder, salt and pepper in a medium bowl. Add beef and gently knead together. Do not overmix. Form into 2 burgers, about the same size as the bread you're using.

Step 2

Coat a medium nonstick skillet with cooking spray and set over medium-high heat. Add the burgers and cook, turning once, until just cooked through, 8 to 10 minutes total.

Step 3

Meanwhile, preheat broiler to high. Combine cheese, mayonnaise, pimientos and scallions in a small bowl. Toast bread.

Step 4

Place toast on a baking sheet. Top each piece with a burger and half the cheese mixture. Broil until the cheese starts to brown, about 2 minutes.