Using a double boiler (or a heatproof bowl over a pot of boiling water), heat the butter and the 1 cup of chocolate chips until just melted and combined into a smooth and glossy texture. Remove from heat.

Whisk sugar into the chocolate/butter mixture. Add the eggs one at a time, whisking after each addition. Add the vanilla and salt, continuing to mix, and then stir in the flour. Stir in the 1/4 cup of chocolate chips. Cover the bowl and chill the dough for at least three hours.

Remove the dough from the refrigerator. Using a cookie scoop or tablespoon, scoop out small round balls of dough. Drop the dough balls into the powdered sugar and roll around to coat. Arrange the powdered sugar-coated dough balls on a parchment paper-lined cookie sheet at least two inches apart. Bake at 350 degrees for 15 minutes, or until cookies have spread and have a light crispy crust on the top. Cool cookies on a wire rack.