In a medium bowl, whisk together the all-purpose flour and salt, and set aside.

In a stand mixer, cream together the unsalted butter and confectioners' sugar until fluffy and light, about 3-5 minutes.

Mix in the freshly grated orange zest and vanilla extract until well blended, then gradually add in the flour mixture, mixing until just combined.

Knead the dough briefly until it forms a ball.

Roll the dough into a log, approximately 12 inches long and 2 inches in diameter, wrap tightly in plastic wrap and chill for at least 2 hours.

Preheat your oven to 325°F (160°C). Remove the log from the refrigerator and unwrap it.

Slice the chilled dough into 1/4-inch thick rounds and arrange on a lined baking sheet.

Bake for 15-17 minutes or until firm to the touch and pale golden, then cool on a wire rack.

While cookies cool, melt dark melting wafers in a microwave-safe bowl, heating in 15-second intervals until smooth.

Dip each cooled cookie halfway into the melted chocolate, allowing excess to drip off, and set on parchment paper to dry completely.