Peel the onions and cut them into thin rings. Place them in a pan with 50 g of butter and EVO oil. Cook over low heat for 10 minutes, add a teaspoon of sugar and continue cooking until the onions are soft. Add the sifted flour and stir for 3 minutes. Blend with white wine and add the broth, letting it boil for at least 30 minutes over medium heat, adding it when needed. When the soup is ready, add salt and pepper. Cut the bread into cubes and brown it in a pan with a tablespoon of EVO oil. Put the slices of bread in the soup, cover with grated Provolone Valpadana PDO and serve.