Once you master ganache (see our handy 101 here), making these melt-in-your-mouth confections is a breeze.
Immediately after making the ganache, add it little by little to peanut butter, whisking constantly, until smooth. Refrigerate in a 5-by-8 1/2-inch glass loaf pan, covered, until firm, 4 hours to overnight.
Scoop with a 1 1/4-inch ice cream scoop, and roll into smooth balls with your palms. (If mixture softens, refrigerate until firm.) Roll each in cocoa, tapping gently to remove excess. Refrigerate in mini baking cups for 30 minutes (or up to 4 days).