Preheat oven to 350 degrees. Sift together flour, baking soda, and salt; set aside.
Put sugar and lemon zest in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium speed 30 seconds.
Add butter; mix until pale and fluffy, about 1 minute. Mix in eggs one at a time; add vanilla and lemon extract. Gradually add flour mixture, and mix until just combined. Stir in crushed lemon drop candies.
Roll into 1-inch balls (I used a #40 ice cream scoop), flatten slightly and bake on parchment-lined baking sheet for 10-12 minutes until edges start to brown and center is almost set. (The cookies spread quite a bit, so I only baked eight cookies per sheet.) Let cool slightly on pan 1 to 2 minutes. Transfer cookies to cooling racks; let cool completely.
Make a glaze by mixing powdered sugar with lemon juice; then spread over cookie tops.