Lightly oil 8 muffin tin holes with spray oil. Sift the flour and salt into a bowl and stir in the cornmeal, 50 g (2 oz) of the cheese, the tomatoes and basil. Make a well in the centre.
Beat the egg, milk and oil together in a separate bowl or jug, pour into the well and stir together until just combined. The batter should remain a little lumpy.
Divide the batter between the prepared muffin holes and scatter over the remaining cheese. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20–25 minutes until risen and golden. Leave to cool in the tin for 5 minutes, then transfer to a wire rack to cool. Serve warm with butter.