Preheat the oven to 375-degrees.
Cream the butter into the shortening using medium speed until blended together, about 1 minute.
Slowly beat the sugar into the butter and shortening, adding about ½ cup at a time on medium speed.
Add the eggs one at a time, beating them into the butter and sugar mixture on low speed.
Stir in the vanilla and lemon extracts along with the lemon zest and juice.
In a separate bowl whisk together the flour, baking powder and kosher salt.
With the mixer on low speed, add the flour mixture into the batter, about ½ cup at a time.
Drop the cookie dough by rounded teaspoons onto a baking sheet lined with a Silpat liner or parchment paper, leaving about 3” between cookies. A small (about 1” diameter) ice cream scoop works really well for this.
Place about ¼ cup flour into a small bowl. Press the cookies with the tines of a fork, in a crisscross pattern. Dust the fork in the extra flour as you go to prevent it from sticking to the cookies.
Sprinkle the extra sugar across the tops of the cookies, about ¼ teaspoon on each.
Bake in a 375-degree oven for 10 to 12 minutes just until the cookies are set and lightly golden on the bottoms.
Let the cookies cool on the baking sheets for about 5 minutes then transfer to a wire rack to cool completely.