Start by preheating your oven to (220°C / 425°F / gas mark 7)
In a large microwave safe bowl, melt the butter and add in the sugar and mix well.
Next, pour in the oil and whisk.
Crack in the eggs and whisk until well combined.
Add in the sour cream, salt and vanilla. Whisk until everything is well mixed. (If you don't have sour cream, simply use greek yogurt instead.)
Next, add in the flour and baking powder and fold till combined, but don’t overmix.
Coat the raspberries and white chocolate chips in 2 tbsp of flour, and coat them really well, they should be well coated in flour. (Crush or chop the raspberries up a bit, if using frozen berries, before coating in flour!)
Add the raspberries and chocolate chips into the muffin batter and fold gently.
Scoop the muffin batter into a lined muffin or cupcake tray, using a large ice cream scoop or a ½ cup measure. You should get 12 muffins.
For the crumble, in a small bowl mix the flour, sugar and butter, with a fork or your fingertips until you have a crumble.
Sprinkle the crumble over the muffins evenly, and lightly pat down.
Bake for 5 minutes at (220°C / 425°F / gas mark 7), then turn the oven down to (190°C / 375°F / gas mark 5) and bake for an additional 15 minutes, until muffins are golden brown and spring back to the touch. Remove from the oven and allow to cool for at least 15 minutes before eating!
Enjoy!