In a medium bowl, whisk the butter and both sugars together until well combined. Mix in the vanilla and salt followed by the flour. Fold in 1 cup (170 g) mini chocolate chips.
Roll the dough into 1 tablespoon size balls and place them on a parchment-lined baking sheet. Chill for 20-30 minutes, until firm.
Place remaining 2 cups (340 g) chocolate chips in a heatproof bowl set over a pot of barely simmering water. Stir continuously until the chocolate is melted and smooth.
Using a candy dipping tool or the tines of a fork, dip each cookie dough ball into the chocolate then tap off any excess. Place the truffles back on the baking sheet and refrigerate until the chocolate is set, about 10 minutes.
