Step 1
In a small skillet, melt butter over medium low heat. Cook diced jalapeño peppers garlic and onion for about 5 minutes or until softened. Stir in salt and pepper. Scrape half of the mixture into a large bowl and reserve remaining.
Step 2
Add beef, breadcrumbs, Worcestershire, and garlic powder to bowl and mix to combine well. Divide into 4 large balls; set aside.
Step 3
Combine reserved jalapeño mixture with cheddar and cream cheeses until smooth. Divide into 4 balls. Press out meat balls large enough to fit one of the cheese balls. Shape the meat around the cheese to seal and form burgers about 1 inch (2.5 cm) thick. Repeat with remaining meat and cheese. Place burgers on a dinner plate; cover and chill for at least 1 hour or up to 24 hours.
Step 4
Place burgers on preheated and greased grill over medium heat. Grill, turning occasionally for about 15 minutes or until juices run clear when pressed. Top each burger with a slice of cheese and a few slices of jalapeño and let melt slightly.
Step 5
Place burgers into buns layered with lettuce, tomato, and onion, if using.
Top 5 Nutrients: Vitamin B12 ≥104%DV, Niacin ≥88%DV, Zinc ≥73%DV, Selenium ≥55%DV, Riboflavin ≥38%DV.