Preheat your oven to 350 degrees Fahrenheit. Prepare a standard-sized muffin tin by placing cupcake liners in each cup.
In a medium bowl, whisk together the all-purpose flour, poppy seeds, baking powder, baking soda, and salt.
In a large bowl or the bowl of a stand mixer, add the unsalted butter and sugar. Beat them together on medium-high speed for about three minutes, until the mixture becomes pale yellow, light, and fluffy.
Beat in the eggs one at a time, making sure each is fully incorporated before adding the next. Add the vanilla extract, lemon juice, and lemon zest.
With the mixer on low speed, add the flour mixture and Greek yogurt in two additions, alternating between the two.
Carefully divide the batter between the muffin liners, filling each about two-thirds full.
Place the muffin tin in the preheated oven and bake for about 17 to 20 minutes, until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for about five minutes before transferring them to a wire rack.
In a small bowl, whisk together the powdered sugar and lemon juice until smooth for the glaze.
Drizzle the glaze over the muffins while they are still warm. Let them cool completely until the glaze is well set before serving.
