Place ¼ cup of the walnuts in a food processor. Add the cacao butter, coconut butter, maple syrup, coconut sugar, maca, vanilla, and salt. Process until well combined. Add the last ¼ cup of walnuts and 2 tablespoons of sweet cacao nubs and process briefly to chop, but leaving a little texture. Spoon into a bowl and refrigerate for about 20 minutes to slightly harden.

Grind the remaining sweet cacao nibs in a spice grinder to form a coarse powder, and place into a small bowl. Use a melon ball scooper to form the truffle mixture into a ball, then carefully roll the ball in the cacao nib powder to dust the outer surface. Place on a plate, and repeat to form remaining truffles. Refrigerate the truffles for one hour longer to set completely, then store at room temperature.