If you are using compressed yeast, mix it with the sugar in a medium bowl, then beat in the warm water. Leave for 10 minutes until frothy. For other yeasts, follow the manufacturer’s instructions.

Sift the flour into a large bowl and make a well in the center. Pour in the yeast mixture, egg yolks, olive oil, and salt. Mix until the dough comes together. Tip out onto a lightly floured work surface. Wash and dry your hands. Knead the dough for 10 minutes until smooth and elastic. It should be quite soft, but if it’s too soft to handle, add more flour.

Place in an oiled bowl, cover with plastic wrap or a damp kitchen towel, and let rise until doubled in size — about 1 hour.

To make the walnut butter, cream the butter and sugar together, then stir in the lemon peel and walnuts. Keep at room temperature.

Uncover the dough, punch out the air, then shape into a ball. Roll or pull the dough into a rectangle to line the prepared jelly roll pan. Spread the walnut butter over the flatbread crust, add the grapes, and sprinkle with brown sugar. Cover with plastic wrap or a damp kitchen towel and let rise for 1 hour until puffy and doubled in size.

Preheat the oven to 400 F. Uncover the dough and bake for 15 minutes. Turn the oven down to 350 F and bake for 20 minutes more or until risen and golden. Let cool slightly before turning out.

To make the Vin Santo cream, beat the cream, confectioners’ sugar and Vin Santo together in a bowl until the mixture forms soft peaks. Cut the focaccia into wedges and serve with the Vin Santo cream.