Thaw the king prawns if frozen by placing them in a colander under cold running water
Pat the prawns dry with paper towels to remove excess moisture
If desired, devein the prawns by making a shallow cut along the back and removing the digestive tract
Set prawns aside on a plate, keeping shells on for maximum flavour and moisture retention
Finely chop the garlic cloves
Finely chop the red chilli, removing seeds for less heat if preferred
Roughly chop a small bunch of fresh parsley; reserve for garnish
Cut one lemon into wedges for serving and juice the other lemon for use in cooking
In a large frying pan, heat the olive oil over medium-high heat until shimmering
Add the king prawns in a single layer to the hot pan and cook for 1–2 minutes on each side until just turning pink; remove prawns from the pan and set aside
Reduce heat to medium and add the butter to the same pan, allowing it to melt and foam
Add the chopped garlic and chilli to the melted butter and sauté for 30 seconds until fragrant, being careful not to brown the garlic
Sprinkle in the sweet paprika and stir rapidly to infuse the butter with spice
Return the prawns to the pan and toss to coat evenly in the buttery chilli mixture
Squeeze in the juice of one lemon and season lightly with salt if needed; toss for another 30–60 seconds, just until prawns are cooked through and glazed
Remove the pan from heat and transfer prawns to a warm serving platter
Spoon any remaining pan sauce over the prawns
Garnish with chopped parsley and arrange lemon wedges on the side
Serve immediately with crusty bread to mop up the buttery sauce