Peel and core the pumpkin. Cut the flesh into small cubes. Peel and finely dice onion. Melt butter, fry onion and pumpkin in it. Season with salt and pepper. Deglaze with 1/2 litre water and milk, bring to the boil briefly.
Add 1 teaspoon of salt, add polenta semolina while stirring continuously. Let it simmer at very low heat for about 15 minutes, stirring from time to time. In the meantime wash, clean, quarter and seed the tomatoes.
Cut the fruit flesh into small cubes. Cut olives into rings. Wash herbs. Chop parsley roughly. Strip rosemary needles from the stems. Mix prepared ingredients, olive oil and vinegar.
Season with salt and pepper. Season polenta again and fill into a greased ovenproof dish (approx. 24 cm Ø). Spread 4 tablespoons of the salsa on top. Grate cheese over it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 10-15 minutes.
Remaining salsa extra is enough.