Mary, since both butter and sugar are stable at room temperature overnight, I wouldn't think there'd be an issue letting them sit overnight, combined, while you wait for a repairman. That said, we're not the ultimate food safety experts here; if you have any doubts, go ahead and refrigerate; in the morning, allow yourself an hour or so for the mixture to come back to room temperature. Good luck — PJH@KAF
April 28, 2019 at 4:44pm
In reply to I was all set to make oatmeal cookies and have my butter, brown… by Mary (not verified)