2) Cook the bacon in a frying pan until just crisp; transfer to a kitchen-paper lined plate with a slotted spoon, leaving the drippings in the pan. Grease a 1.5L shallow baking dish with some of the drippings and dust with 2 teaspoons of polenta. Place on a baking sheet.
3) Add the milk to the remaining bacon fat in the pan and bring to a boil over a high heat. Whisking constantly, gradually pour in the remaining polenta. Add 1 teaspoon of salt, the sugar and the cayenne. Lower the heat to a simmer, whisking, until thickened, about 3 minutes. Stir in the corn, spring onions and bacon; remove from the heat.
4) Beat the eggs with an electric whisk until very pale and fluffy, about 5 minutes; add the baking powder. Stir a quarter of the whisked eggs into the polenta mixture, then carefully fold in the rest. Pour the batter into the prepared baking dish and bake until puffed and golden, about 50 minutes.
5) For the tomatoes: Toss the tomatoes, olive oil and herbs in a bowl with salt and black pepper to taste, set aside for at least 5 minutes. Let the spoon bread rest for 10 minutes, then serve with the tomatoes.