01 - Preheat the oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper.
02 - Whisk together flour, poppy seeds, baking powder, baking soda, and salt in a medium bowl.
03 - Beat softened butter and granulated sugar in a large bowl until light and fluffy, about 2-3 minutes.
04 - Beat in eggs one at a time, mixing well after each addition.
05 - Mix in Greek yogurt (or sour cream), lemon zest, lemon juice, and vanilla extract until combined.
06 - Gently fold dry ingredients into wet ingredients until just combined. Avoid overmixing.
07 - Transfer batter to prepared loaf pan and smooth the top evenly.
08 - Bake for 45-55 minutes until a toothpick inserted into the center comes out clean.
09 - Let cool in pan for 10 minutes, then transfer to wire rack to cool completely.
10 - Whisk powdered sugar and lemon juice until smooth and pourable. Drizzle over cooled loaf and allow glaze to set before slicing.