Prep the Batter: Preheat the oven to 350°F (180°C). Grease or line a 12-cup muffin tin.In a large bowl, whisk 1 large egg, ¾ cup sugar, ¾ cup Greek yogurt, ¼ cup olive oil, ¼ cup milk, the zest of 1 large lemon, ¼ cup lemon juice, and 2 teaspoons vanilla extract until smooth and well combined.
Add the Dry Ingredients: Stir in2 tablespoons poppy seeds then add 1⅔ cup all-purpose flour, 2 teaspoons baking powder, ½ teaspoon baking soda, and ¼ teaspoon salt (sift if possible).Stir gently with a spoon or spatula just until the batter comes together—avoid overmixing.
Fill the Muffin Pan: Spoon the batter evenly into the muffin cups.Optional: top with a sprinkle of brown sugar or slivered almonds.
Bake and Cool: Bake for about 23 minutes, or until a toothpick inserted comes out clean or with a few crumbs.Let the muffins cool in the pan for 10 minutes, then transfer to a rack to cool completely.