Melt the butter in a large skillet over medium-high heat. Add the nectarines and cook, stirring occasionally, until the skins are charred and the flesh is tender, 10 to 15 minutes. Remove from the heat and set aside to cool. In the bowl of an electric mixer, beat the ricotta cheese until soft peaks form. Gradually add the confectioners' sugar, beating after each addition until fluffy. Fold in the honey and orange zest. Transfer the mixture to an airtight container and refrigerate until firm, at least 1 hour. Serve with toasted almonds.