Add the pitted Medjool dates and nut butter to a food processor. Blend for 2–3 minutes, pausing as needed to scrape down the sides, until the mixture becomes thick and mostly smooth. It will be very dense—if your food processor struggles, add a tiny splash of water to help it along.

Scoop the mixture into 24 even portions (about 1 heaping tablespoon each) and roll into balls. Place on a parchment-lined baking sheet and freeze for 10 minutes to firm up.

Meanwhile, melt the dark chocolate in a microwave or double boiler. Dip each chilled ball into the melted chocolate, letting excess drip off, then place back on the parchment-lined sheet.

If desired, sprinkle with sea salt flakes while the chocolate is still wet. Return to the freezer for 20 minutes, or until the chocolate is set.

Store truffles in an airtight container in the freezer for up to 2 weeks. Let sit at room temperature for 10 minutes before serving.