Preheat oven to 350 degrees F (180 degrees C). Butter and flour a 10-cup capacity bundt pan, and set aside.
In the bowl of a stand mixer fitted with paddle attachment over medium high speed, cream together Butter (3 stick) and Caster Sugar (5 cup) for 4-6 minutes. It should be fluffy and creamy. Add the Egg (5) one at a time, mixing well after each addition, make sure to scrape the bottom and sides of the bowl.
Add Baking Powder (2 teaspoon), Salt (1/2 teaspoon), Vanilla Extract (1 teaspoon), and Sour Cream (1 cup). Mix until well combined. Add Pure Lemon Extract (1 tablespoon), All-Purpose Flour (3 cup), and Lemon (2 tablespoon) and mix on low speed until flour is incorporated.
Pour batter in prepared bunt pan, spread the batter batter evenly. Bake for 1 hour and 10 minutes or until a toothpick inserted comes out clean.
Make glaze by mixing Powdered Confectioners Sugar (1 cup) and Lemon Juice (2 tablespoon). Allow pound cake to cool completely. Once the pound cake is cooled, drizzle over the lemon glaze.