Use a non-stick baking sheet. Preheat oven to 220 degrees C. Sift the flours, baking powder and salt into a bowl; tip in any bran left in sieve. Rub in butter until mixture resembles fine bread-crumbs. Stir in Parmesan cheese.
Make a well in the centre and pour in the milk. Mix together to make a fairly soft dough. Knead briefly until smooth.
Roll out the dough on a lightly floured work surface to 5mm thickness. Cut out 6 rounds about 10cm in diameter. You will need to re-roll the trimmings to cut out the last round. Transfer rounds to baking sheet; space them well apart. Mark edges with a fork.
Brush tops with 2 teaspoons olive oil. Mix the remaining oil with the garlic, tomato paste and basil and spread thinly over rounds, leaving a clear border of about 5mm. Arrange tomato slices on top, over-lapping them slightly and covering all of the basil topping.
Bake for 7 minutes, then scatter the pine nuts over the tomatoes. Return to the oven and bake for 3–5 minutes or until the galettes are risen and the edges are golden brown. Serve hot, garnished with basil leaves.