I used 2 mini muffin trays, lined with silicone liners. Very durable, high-quality paper liners work well, too!
Place 1-2 Tablespoons of natural nut butter in the bottom of each liner. Press gently, so they fill the cups, & get the nice creases.
Melt the chocolate, milk, and coconut oil by whisking continuously until smooth, on the stove top on medium heat. Double broiler method also works really well.
Once the chocolate, milk, & oil have combined and are smooth, pour a little bit of this chocolate mixture on top of the PB in each muffin cup.
Place pans in the freezer for about 2 hours to completely set.