i want to make a cake today. I don't have caster sugar. I do have granulated and soft light brown can I use these or is there a better recipe to use them?
The type of sugar you use in a cake will partly depend on the type of cake you are making. As soft light brown sugar has more moisture and some flavour from molasses it is fine to use in chocolate cakes, brownies and banana based cakes. However it would be a little too strong for lighter butter cakes such as Victoria Sponge, madiera cake, pound cake and vanilla cupcakes. For these you need a more refined sugar where the flavour of the sugar will not overwhelm the other ingredients.
Generally caster (superfine) sugar is preferable for creamed cakes as the smaller crystals will dissolve quickly as it is beaten with the butter whereas granulated sugar doesn't always fully dissolve during the creaming stage (and not if using an all-in-one method) and you may get small crystals of sugar left which will affect the texture of the baked cake. Note however that US granulated sugar tends to be finer than UK granulated and is more commonly used in cakes. If you only have granulated sugar then it would be best to look at cakes made using a melted method, such as sticky gingerbread, some muffins, banana bread or Nigella's Chocolate Guinness Cake from Feast (p286) , adding the granulated sugar to the saucepan with the butter so that it melts thoroughly.