Set the oven to 200 degrees. Melt the butter, set aside and let cool a little. Whisk eggs and ProPud Milkshake until fluffy in a bowl. Mix flour, baking powder and vanilla sugar in another bowl. Mix in the egg and milkshake mixture. Mix gently to a smooth and even batter. Divide the batter into muffin tins. Bake in the middle of the oven for about 15 minutes.