Muffins alla Zucca(squash) e Noci(walnuts)

300 grams sifted all purpose flour 250 grams sugar 200 grams melted butter A pinch of salt 250 grams squash, cooked and mashed 75 grams of chopped walnuts 6 egg yolks 6 egg whites, beaten until stiff( you can add 5 grams of cream of tartar or a pinch of salt to help you in…