- Mix butter, parsley and cheese in a bowl, beat until smooth.
- Lay a piece of plastic wrap on a work surface, mound butter in the center.
- Roll and shape into cylinder, seal the ends.
- Chill in the fridge for one hour or until firm.
- Unwrap the butter roll and cut crosswise into 2 cm thick slices, keep refrigerated.
- Divide meat into four portions, and then divide each portion into two.
- Pat one portion in a cookie cutter (ring), place a slice of butter in the middle, top with the other portion and press lightly to seal and form a patty.
- Season with salt and paper, cover and refrigerate for 30 minutes.
- Preheat the grill on high, brush with oil.
- Place the burgers on the hot grill, cook for about 5 minutes per side, or until cooked through.
To Assemble
- Place the bottom half of each bun in serving plates.
- Top with lettuce leaf, slices of onion and tomato.
