Cut the butter into pieces. Mix butter, flour, hazelnuts, parmesan and 1 pinch of salt to crumble and chill for about 30 minutes
Carve tomatoes crosswise, blanch with boiling water, let stand briefly. Quench tomatoes, peel skin. Quarter tomatoes and cut into pieces. Drain capers. Wash and clean spring onions and cut into rings
Heat the oil in a pan, stir-fry the spring onions for 2-3 minutes, sprinkle with cane sugar and allow to caramelize. Add diced tomatoes and cook for about 5 minutes. Remove from heat and season with salt and pepper. Add capers
Spread the tomato mixture on 4 small ovenproof baking dishes and cover with crumbles. Bake in the preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes until golden brown