Preheat the oven to at 350 °F. Butter and flour a 9"x5" loaf pan or Bundt pan.
In a small bowl, whisk together the 3 large eggs, 2 yolks, 1 teaspoon vanilla extract1 teaspoon real lemon extract, finely grated zest from 1 lemon and half of the yogurt. Set aside.
Sift together 8 oz cake flour,¼ teaspoon table salt, 1 teaspoon baking powder into a mixing bowl. Add 10 oz granulated sugar to the flour and mix at low speed for 30 seconds. With the mixer running on low speed, add 9 oz unsalted butter to the flour and mix until combined. Add the other 1/2 of the yogurt and increase the speed to medium high. Mix for a full 2-3 minutes. The batter will lighten in color and texture. If your using a hand mixer add another minute or two to the mixing time.
Scrape the bowl and paddle thoroughly. On low speed, add the egg mixture in 3 increments, scraping the bowl after each addition.
Pour the batter into the prepared pan and smooth to an even layer. Use the tip of the spatula to form a groove down the center of the batter. This is where the pound cake will split.
Bake until a toothpick inserted in the middle comes out clean (about 55-65 minutes).
While the cake is baking make the syrup. Combine 4 oz fresh lemon juice and 4 oz sugar in a small saucepan. Heat until the sugar is melted and the syrup begins to boil. Let the syrup simmer for 30 seconds then turn off the heat. Set aside until the cake is ready.
As soon as the cake comes out of the oven, brush all of the syrup over the top of the cake. Let the cake cool 20-30 minutes, or until all the syrup is absorbed, before removing from the pan.
Cool completely in a wire rack before slicing. The flavor gets better if the syrup has several hours or a day to absorb into the cake.