Put the flour and margarine in a large mixing bowl and crumble. It should look like breadcrumbs.
Now slice the apple and add it to a small baking dish. This is where you can add the raisins as well. Sprinkle with half of the sugar and a few drops of lemon juice to prevent the apple from turning brown. Stir half of the butter mixture into the apples.
Stir the remaining half of the sugar into the rest of the butter mixture, and spread on top of the apple slices.
Place in the oven until it is a golden brown color. Normally this would take around 10 to 15 minutes. Allow to cool for 2 minutes and enjoy.