Preheat the oven to 350°F. Spread the pecans in a single layer on a baking sheet. Toast for 6-8 minutes then set aside to cool completely. (This can be done in advance)
To Make the Cookies: Leave oven temperature at 350°F. Line 2 large sheet pans with parchment paper or silicone baking mats.
In a large mixing bowl use an electric mixer on medium-high speed to cream together the brown sugar, butter and vanilla beating for 1-2 minutes or until fully combined. Add the egg and corn syrup. Beat until incorporated.
In a separate medium bowl, use a whisk to sift together the flour, baking powder and salt. Lower the speed of the mixer and gradually add flour mixture to the creamed mixture beating on low speed just until combined.
Chop the pecans in a food processor or nut chopper. Mix 1 1/4 cup into the cookie dough reserving 1/4 cup for garnishing. Use a rubber spatula to fold the pecans into the cookie dough by hand until the pecans are evenly distributed throughout.
Using a Tbsp or small cookie scoop drop dough rounds onto the parchment lined baking sheets leaving at least 3-inches apart. Gently flatten into a circle using a spatula or back of a spoon.
Bake for 8-10 minutes in batches or until the edges are golden brown.
Remove cookies from the oven and use a knife or the sharp edge of a cookie spatula (or icing spatula) to shape the edges into uniform circles, if needed.
Cool lace cookies on the pan for 5 minutes then carefully remove to a cooling rack to cool completely.
Melt Chocolate: In a microwave safe bowl, melt together the chocolate chips and shortening in 20 second increments stopping to stir each time. Repeat the process until completely smooth.
Dip one edge of each cookie into the melted chocolate laying on a wax paper lined sheet pan to dry and set.
Sprinkle with reserved chopped pecans while the chocolate is wet then allow to dry completely.