Preheat oven to 325°. Place pecans in a single layer on a baking sheet. Roast pecans for 10-15 minutes or until toasted and fragrant.
Transfer pecans to a mini prep food processor and chop finely, but don't grind. You can also use a cutting board and knife to chop the pecans very finely. Set aside to cool.
In a large mixing bowl (of a stand mixer if you have it) mix the butter and sugar until combined. Add the vanilla and mix until blended into sugar mixture.
Sift together the flour and salt and add it to the butter mixture and blend on low speed until dough just starts to come together.
Add the toasted pecans to the dough and mix on low speed until combined.
Divide the dough in half and transfer to a lightly floured work surface. With your hands, form the dough into a 1" thick rectangle. Do the same with the other half of the dough and refrigerate for 30 minutes.
Remove one half of the dough and place it on a lightly floured work surface. Gently roll the dough to 1/2" thick. Use a clean ruler to measure the rectangle. You want the short side of the rectangle to measure 3". Use the flat edge of the ruler and a pizza cutter to trim away the excess dough so that it measures 3" and the edges are straight. Use the pizza cutter to cut 1" slices in the dough -- so that you wind up with 3" x 1" shortbread fingers. Transfer the fingers to a parchment lined baking sheet. Note: if you space the shortbread apart on the baking sheet it will spread slightly. If you place the shortbread so that the sides are touching they will bake together, but are easily snapped apart after cooling.
Use the flat end of a wooden skewer to make 3 slight indentations down the center of each cookie. Sprinkle the shortbread with sparkling sugar. Continue in the same manner with the other half of the shortbread dough.
With the oven preheated to 325°, bake the shortbread for 18-25 minutes or until lightly golden brown. Let the cookies cool on the baking sheet to room temperature.
Break the chocolate into small pieces and place in a microwave safe bowl. Microwave on high in 20 second increments, stirring after each, until the chocolate is smooth and glossy.
TO DIP THE CHOCOLATE:
Transfer melted chocolate to a small, vertical container, like a juice glass (This gives the melted chocolate a deeper vessel for dipping). Dip one end of the shortbread into the chocolate and transfer to a parchment lined baking sheet. Sprinkle the chocolate end lightly with sea salt. Let the chocolate rest for 30 minutes to an hour until the chocolate has solidified.
TO DRIZZLE THE CHOCOLATE:
If you'd rather drizzle the chocolate over the shortbread, place the shortbread on a parchment lined baking sheet. Use a teaspoon to scoop up the melted chocolate and drizzle in a zig zag fashion over the cookies. Sprinkle with the sea salt and let the shortbread rest for 30 minutes to an hour for the chocolate to set.