How ingredients are mixed together can make or break a successful outcome when baking. Directions are given to combine certain ingredients and should be followed. For example, in making a layer cake, there are two methods, the creaming and reverse-creaming techniques.
The creaming method starts by beating the sugar and butter together until light and fluffy. The sugar crystals beat little air pockets into the fat. Then the wet and dry ingredients are added in a dry-wet-dry-wet-dry pattern to reduce gluten development and make a tender cake. During baking the air pockets made during creaming, leaven or lift the cake to give a light airy structure. The top typically has a slight dome.
The reverse-creaming method starts by mixing butter with all of the dry ingredients. The butter fat coats the flour particles making the flour waterproof. The liquid is added but only some flour proteins will get hydrated. This limits gluten development and increases tenderness. Without incorporating air, the cake will be a bit shorter, have a flatter top and will be quite tender. This is better for fancy, multiple layer cakes.