Preheat the oven to 250°F/120ºC/gas mark ½. Line a baking tray with greaseproof paper.

Whisk together the oil and a pinch of salt in a large bowl, add the tomatoes and toss to coat. Arrange the tomatoes, cut-side up, on the lined tray and roast for 2 hours until soft and sticky.

For the polenta, bring a large pan of water to the boil, add the spinach leaves and cook for 1 to 2 minutes until wilted. Drain thoroughly, then squeeze dry using plenty of kitchen paper. Roughly chop and set aside. Pour the stock into the spinach pan and bring to the boil, then whisk in the polenta, ensuring that you whisk constantly to prevent the polenta from turning lumpy. Reduce the heat and cook slowly, stirring regularly, for 30 to 35 minutes until the polenta has thickened and starts to pull away from the sides of the pan. Remove the pan from the heat, whisk in the butter and Parmesan and then fold in the spinach and blue cheese. Divide the polenta between 14 warmed serving bowls and top with the sticky roasted tomatoes.