Preheat the oven to 160 degrees Celsius.
In a large pan bring the stock to boil. Add the polenta stirring continuously. Once the polenta starts to splutter turn the heat down low and simmer, stirring occasionally, for 20 minutes or until cooked. (Polenta is cooked when it comes away from the side of the pan and the spoon stands up on its own). Remove from the heat and using a rolling pin roll the polenta out to approx 4mm thick. Set aside to cool.
Cut the tomatoes in half and place on a baking sheet lined with baking paper. Brush lightly with olive oil and bake for approx 30 minutes.
Using a biscuit cutter, cut mini rounds out of the polenta and place on a grill. Brush with a small amount of olive oil and grill for 5 minutes each side to crisp the outside.
Spoon a teaspoon of pesto onto each round and top with a roasted tomato.
Note: Polenta is made from ground corn. It is gluten free and therefore safe for people suffering from coeliac disease.