Preheat the oven to 350° F. Spray a 9×5 inch loaf pan with nonstick cooking spray and set aside.
In a medium bowl, whisk together the flour, sugar, baking powder, and salt. Set aside.
2 cups all-purpose flour, 1 cup sugar, 1 Tablespoon baking powder, 1/4 teaspoon salt
In a separate bowl, whisk together the egg, milk, oil, vanilla, lemon zest, lemon juice, and poppy seeds until well combined.
1 egg, 2/3 cup milk, 1/2 cup vegetable oil, 1 teaspoon vanilla, 3 Tablespoons lemon zest, 3 Tablespoons lemon juice, 1 Tablespoon poppy seeds
Add the dry ingredients to the wet ingredients and stir until just combined and moistened. Do not overmix.
Pour the batter into the prepared loaf pan and spread evenly.
Bake for 45–50 minutes, or until a toothpick inserted in the center comes out clean.
Let the bread cool in the pan for 10 minutes, then remove and transfer to a wire rack to cool completely.
To make the glaze, whisk together the powdered sugar and lemon juice until smooth.
1/2 cup confectioners sugar, 1 Tablespoon lemon juice
Drizzle the glaze over the cooled bread and let it set before slicing.