Preheat the oven to 220 deg C/425 deg F/gas mark 7.
Sift the flour, baking powder, salt and pepper into a large bowl.
Rub in the butter and add two-thirds of the Cheddar and goat's cheese, olives, tomatoes and basil, reserving the remaining third for the topping. Mix well.
Beat the egg and milk together and add to the dry ingredients, working quickly and lightly with a large fork until the flour is just incorporated. I keep my movements large to allow as much air as possible into the mix and am very careful not to over-beat - less than 30 seconds is enough.
Lightly butter and flour the muffin tin (or line with muffin papers) and fill each two-thirds full, sprinkling the remaining bits on top.
Bake in the middle of the oven for 18-20 minutes until well risen and golden. Remove from the oven and allow them to cool for 5 minutes before loosening with the tip of a knife and transferring to a wire rack.