Prehat oven to 195C / 175C Fan / Gas Mark 5. Line a Muffin tray with cupcake cases. 

Place the streusel topping ingredients into a bowl. Using your fingertips, rub together until it resembles large breadcrumbs. 

Sieve the plain flour and the baking powder together into a large mixing bowl. Stir in the caster sugar, 100g white chocolate chips and the raspberries. Then make a well in the middle. 

In a bowl beat two eggs until just combined, continue to beat adding in the milk, melted butter and vanilla extract. Pour into the centre of the dry ingredients. 

Use a fork to gently fold the mixture. It will seem slightly lumpy but that is fine as you don't want to over mix or the muffins will become dense and tough. 

Divide the mixture evenly between the cupcake cases, then sprinkle the streusel topping over each one. 

Bake for 25-30 minutes until golden brown. Insert a skewer into the middle, if it comes out clean the muffins are ready. Leave the muffins in the tray and allow to cool for 10 minutes then remove and place onto a wire rack. 

To decorate melt the remaining chocolate chips according to package instructions and drizzle lightly over each of the muffins.