Heat butter, oil and garlic in a medium frying pan over medium-high heat until butter has melted.
Add flour and cook, stirring for 1 minute or until mixture bubbles.
One at a time, add ¼ cup of the stock, stirring constantly to prevent lumps forming.
Add wine and cream.
Cook, stirring for 3 minutes or until sauce boils and thickens.
Add mustard and seasoning, to taste.
Add prawns and simmer, stirring for 3 minutes or until prawns are cooked through.
Stir in parsley.
Serve creamy garlic prawns with steamed rice.
