Line baking sheet with parchment paper.
In food processor, pulse pecans and walnuts until meal; scrape into bowl.
Pulse dates to form ball.
Add cocoa powder, maple syrup, vanilla, salt and nut mixture; pulse, scraping down side as needed, to form loose dough.
Using melon baller or tablespoon, drop by rounded 1 tbsp onto prepared pan; gently roll into balls.
Freeze until firm, about 15 minutes.
Meanwhile, in microwaveable bowl, microwave chocolate chips with coconut oil on high, stirring every 30 seconds, until smooth, about 1 ½ minutes. Don't overheat.
Using 2 forks, dip each truffle into chocolate mixture, tapping forks on edge of bowl to remove excess.
Return to pan; sprinkle with toppings (if using).
Refrigerate until coating hardens, about 15 minutes.
(Make-ahead: Refrigerate in airtight container for up to 1 week or freeze for up to 1 month.)
