Combine the butter, powdered sugar, cocoa powder, vanilla, and salt in a large bowl. Using a hand mixer, beat the mixture until creamy, about 2 minutes. Add the flour, pine nuts, and chocolate. Stir until just mixed.
Line 2 baking sheets with parchment paper. Scoop out 1-inch balls of dough. Place on the cookie sheet. Bake until the tops look dry, about 18 minutes. Let cool for 15 minutes on the baking sheets. Dust with powdered sugar and transfer to a serving plate.