Spread the hazelnuts on a baking tray and roast in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for 6-8 minutes.
In the meantime, wash the grapes, drain them and cut them in half. Clean and wash the lettuce, cut it smaller if necessary and spin dry. Cut circles (approx. 2.5 cm Ø) from the bread slices with a round cookie cutter.
Take the nuts out of the oven and let them cool down on a flat plate. Heat 2 tablespoons of oil in a frying pan and fry the slices of bread for approx. 4 minutes, turning them until golden brown. Drain on kitchen paper.
Mix vinegar, honey and mustard in a bowl. Fold in 4 tablespoons of oil in a thin stream. Season to taste with salt and pepper.
Roughly chop the nuts. Mix with salad, dressing and grapes. Arrange on plates. Cut cheese into 4 slices. Place them side by side on a baking tray lined with baking paper and grill under the hot grill of the oven for 2-3 minutes.
Place each slice of cheese on a piece of bread and arrange on the salads.