This lemon poppy seed sheet cake is a crowd-pleasing dessert that is perfect for any party or gathering. The cake is made with all-purpose flour, baking powder, salt, sugar, eggs, vegetable oil, lemon zest, lemon juice, poppy seeds, and milk. The ingredients are mixed together and poured into a greased sheet pan. The cake is baked in a preheated oven for about 25 minutes. Once the cake is done, it is cooled and then topped with a lemon glaze made with powdered sugar and lemon juice. This cake is perfect for serving at a potluck or picnic.