Starbucks Copycat Lemon Pound Cake

For me this is the best closest recipe to the moist Starbucks lemon pound cake. I've tried so many times to reach the flavor and texture but none of recipes out there were close enough to perfection except this one.

Ingredients:
250g butter, room temperature
250g caster sugar
2- 3 bio lemon, we need about 3 tsp of grated lemon zest and 120ml of lemon juice
4 eggs (medium)
200g all purpose flour
50g corn starch or maizena
2 tsp baking powder
1/4 tsp salt
1/2 tsp vanilla paste or extract
150g powdered sugar

1. In a large mixing bowl, with a hand or standing mixer beat butter, sugar, grated lemon zest until light and fluffy about more than 5 minutes. 
2. In a separate bowl, stir flour, baking powder, salt until combined. Sift it and set it aside. Preheat oven for 180 °C. Slightly butter 25 cm loaf pan and line it with parchment paper.
3. Add the eggs one at a time, beat until well combined on each addition. Add vanilla paste and beat for another 2 minutes. 
4. Take only about 80ml of lemon juice, the rest 40ml is for frosting. Pour 1/3 of the lemon juice to the cake batter and 1/3 of the sifted flour mixture. Beat with low speed until well combined. Repeat process. Mix just until fully incorporated. Do not over mix the batter after the flour went in.
5. Pour the batter into the prepared pan. Bake for about 50 minutes or until toothpick inserted in the middle comes out clean. Let it cool for about 20 min before frosting.
6. For the frosting: In a bowl combine powdered sugar and 40ml lemon juice, stir until no clumps are visible.
7. Drizzle the frosting evenly over the cake. Let it stand for 10 minutes in the refrigerator before serving.