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Appears to be a Variation #3 of the No. 31 Danish Cake Pan according t0 the Griswold Muffin Pan (YB) book. The BB p.116 dates it around 1900 but that page also said it had the number 31 on the underside which would be the variation #4. Yours could be earlier than 1900 but if so I wouldn't think much more that a year or so.