Cheese and Onion Scones - Bake with Amy

Ingredients

• 3 ⅓ cups self-raising flour, sifted (416 gr)
• 1 tsp baking powder
• ½ cup unsalted butter, cold (113 grams)
• ½ cup strong cheese, grated (113 grams)
• 1 small onion, thinly diced
• 1 tsp fine salt
• 1 tsp ground black pepper
• 1 tbsp English mustard
• 275 ml whole milk
• 1 egg yolk
• 1 tsp milk
• extra grated cheese