Preheat your oven to 325°F (160°C). Grease and flour a 9x5 inch (23x13 cm) loaf pan, or spray with a non-stick baking spray with flour. Set aside.

In a large mixing bowl, using an electric mixer (stand or hand-held), cream together the softened unsalted butter and granulated sugar on medium-high speed until light and fluffy, about 3-5 minutes. Scrape down the sides of the bowl as needed.

Add the large eggs one at a time, beating well after each addition until fully incorporated.

In a separate medium bowl, whisk together the sifted all-purpose flour, baking powder, and salt.

In another small bowl or measuring cup, combine the whole milk, fresh lemon juice, lemon zest, and vanilla extract.

With the mixer on low speed, gradually add the dry ingredients to the wet ingredients, alternating with the milk mixture, beginning and ending with the dry ingredients. Mix until just combined; do not overmix. Scrape down the sides of the bowl once more to ensure everything is incorporated.

Pour the batter evenly into the prepared loaf pan.

Bake for 60-70 minutes, or until a wooden skewer or toothpick inserted into the center of the cake comes out clean.

Allow the cake to cool in the pan for 15-20 minutes on a wire rack before carefully inverting it onto the rack to cool completely.

While the cake cools, prepare the lemon glaze. In a small bowl, whisk together the sifted powdered sugar and 3 tablespoons of fresh lemon juice until smooth. If the glaze is too thick, add more lemon juice, 1/2 teaspoon at a time, until it reaches a pourable but not too thin consistency. Stir in the optional lemon zest.

Once the pound cake is completely cool, place the wire rack with the cake over a piece of parchment paper or a plate to catch any drips.

Pour the lemon glaze evenly over the top of the cooled cake, allowing it to drip down the sides.

Let the glaze set for about 15-20 minutes before slicing and serving.