Cream butter, sugar, and cream cheese with whisk attachment. Add peppermint oil, evaporated milk, and cream. Beat on high until fluffy and smooth, 2 minutes. Scrape sides and beat another 30 seconds. Scrape onto parchment, wrap, and refrigerate to stiffen like a paste.

Weigh out 1/2-ounce portions and roll into smooth balls. Press into neat patties. Freeze 1/2 hour.

Melt chocolate and coconut oil over simmering water. Blend very well.

Drop patties 2 at a time into chocolate. Retrieve with candy fork, let excess chocolate run off, then place on parchment to cool. Store in the refrigerator.