Preheat grill to medium or oven broil to high
In a bowl combine cream cheese, cheddar, salsa, garlic powder, and jalapeno.
Combine meat, salt, pepper, and onion.
Divide meat into 8 even pieces and flatten to 1/4-inch thickness.
Divide cream cheese mixture into 4 equal portions and flatten each into a pancake shape.
Place each cream cheese mixture on top of 4 flattened meat portions. Top each with another flattened portion and seal the edges (see photo in post_.
Brush burger with olive oil.
Grill burgers over medium heat 6-7 minutes on each side
Place burgers on a foil-covered pan approximately 6" from broiler. Broil 5-6 minutes on each side
For Air Fryer: Air fry 5 minutes each side at 400F/200C. Bear in mind that your model (see post body) may need adjustment.