Ravioli di Ricotta e Bietola

These ravioli are stuffed with a Swiss chard filling flavored with ricotta and Grana Padano and bound with an egg. The Swiss chard leaves are blanched (see “Le Tecniche: Sbianchire”) in heavily salted boiling water, chilled rapidly in a bowl of ice water, then squeezed out well—first by hand and then in cheesecloth—to prevent the filling mixture from being too wet. The ravioli are sauced with melted butter into which the flavors of marjoram and thym