Combine cheese and sugar. Crema well. Add egg yolks, one at a time. Blend thoroughly. Whip cream and add vanilla and salt. Beat egg whites until stiff peaks form. Fold whipped cream and egg whites into cheese mixture, one at a time. Spread half of crushed graham crackers in the bottom of an 8 x 8 inch pan. Spread on the cream cheese mixture. Sprinkle other half of cracker crumbs on top. Freeze.