Preheat your oven to 190C.
In a large bowl, whisk together the eggs, butter, sugars, yogurt, and vanilla until smooth.
Add in the flour, baking powder and salt. Mix, adding splashes of milk in a few tablespoons at a time to help ease it into a smooth batter.
Mix in the blueberries with a spatula.
Line or grease a jumbo muffin tin and equally portion the batter into each cup. Sprinkle with a generous pinch of brown sugar.
Bake for 20-30 mins (depending on how big you've make them!) until a skewer comes out clean.
