method
1. Bring the stock to the boil in a large saucepan, then gradually stir in the polenta.
2. Continue stirring the polenta over a moderate heat for about 5 minutes, until the mixture begins to come away from the sides of the pan. Stir in the chopped sage and season well, then spoon into a lightly oiled, shallow 23 x 33 cm (9 x 13 inch) tin and spread evenly. Leave to cool.
3. Preheat the oven to 200°C (400°F). Cut the cooled polenta into 24 squares using a sharp knife.
4. Arrange the polenta overlapping with tomato slices in a lightly oiled, shallow ovenproof dish. Sprinkle with Parmesan and bake for 20 minutes or until golden brown. Serve hot.
