Preheat the oven to 350 degrees F.
In a large bowl or the bowl of a stand mixer fitted with the paddle, whisk together the flour, baking soda, baking powder, cornstarch, sugar and salt.
Whisk the butter into the flour until incorporated, a few seconds.
In another bowl, mix the yogurt, vanilla extract and lemon juice and zest until combined.
Add the liquid mixture to the flour in two batches, mixing thoroughly with a spatula after each addition. Make sure you scrape the bottom and sides of the bowl after each addition. If using a stand mixer, mix for 20 seconds after each addition.
Prepare a loaf pan by coating it with cooking spray and placing a piece of parchment at the bottom to make unmolding easier.
Scrape the batter into the pan. It will be quite thick. Smooth the top wth the spatula.
Bake in the preheated oven for 45 to 50 minutes or until a toothpick in the center comes out clean. The top will crack, but that's typical of pound cake batters and actually gives your cake a nice look.
Cool the cake on a rack for 10 minutes, then unmold it and continue cooling it on the rack.
Once the cake has nearly cooled, prepare the glaze by mixing the confectioners' sugar with the lemon juice and vanilla, if using. Drizzle it over the pound cake, and reserve some glaze to drizzle over individual slices.