For the streusel topping, mix butter, sugar and flour together. Then use fingers to crumble it together.

In a large bowl, cream the butter and sugar together. Then add in egg and yogurt, mix well.

Add in flour, baking powder and raspberries, fold it gently.

Divide the batter into lined muffin tin, sprinkle the streusel on top. Pop in preheated oven at 180C, bake for about 18-24 minutes.