I often get asked for this recipe. The original is from BBC Good Food, but I have amended it quite a lot so there is less butter and sugar in it and a bit more "crunch".
Mix the plums with the caster sugar and the spice plus a small pinch of salt and set aside to macerate.
Mix all the dry ingredients together, then mix with the melted butter and golden syrup.
Grease a square tin, approx. 20 x 20cm. Press half the oaty mix over the base of the tin, the spread the fruit in and even layer. Press the remaining oats over the fruit so it is completely covered.
Bake for 45 t 50min until dark golden. Leave to cool completely before cutting it into 16 pieces.
Officially it will keep for two days in an airtight container or frozen for up to a month (and it freezes well). In reality both these times can be longer.