Tasty cheese and red onion scones

Ingredients

• 50 gram butter
• 1 red onion, thinly sliced
• 2 cup self-raising flour
• 1 cup grated tasty cheese
• 1 teaspoon dried basil
• 1 teaspoon mustard powder
• 1 cup milk
• 1 egg, beaten
• 2 tablespoon water
• butter, to serve