The first step of the recipe for vanilla muffins is the preparation of the products. Melt the butter in a water bath, remove the eggs from the refrigerator, sift flour with baking powder. Beat the eggs with the sugar with mixer, wire or stirring with a fork. Add yogurt and mix again, and add the butter. To the liquid mixture add the sifted flour with baking powder little by little, stirring constantly until a uniform mixture. Finally, add the vanilla and beat again. Each slot format for muffins put on a paper basket and 3/4 full by volume. Be careful not to fill up forms for muffins too, because during baking muffins increase the volume, and if the mixture in the trays is more than necessary will overflow and will not bake. If you use a silicone muffin form is not necessary to put paper baskets, just coat the form with advance sunflower oil and pour the mixture. Bake vanilla muffins in a preheated 180C degrees oven for 20 minutes. Check that the muffins are baked as buchnete with a toothpick if it is dry - the muffins are ready.