Apple Cinnamon Muffins

Ingredients

• 400 g self raising flour (sifted)
• 1 tsp baking powder
• 350 g brown sugar
• 200 g unsalted butter
• 200 g greek yogurt
• 3 eggs
• ½ tsp vanilla extract
• 1 tsp cinnamon
• 4 apples
• 1 tbsp brown sugar