Prep the pan and oven. Heat the oven to 400°F (200°C). Line a 12-cup muffin tin with paper liners or grease lightly.
A hotter start helps create a taller dome.
Mix the dry ingredients. In a large bowl, whisk 2 cups all-purpose flour, 3/4 cup sugar, 2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, and 2 tablespoons poppyseeds. Add the zest of 2 lemons and rub it into the sugar with your fingers to release the oils.
Combine the wet ingredients. In a separate bowl, whisk 2 large eggs, 1 cup Greek yogurt (or sour cream), 1/2 cup milk, 1/2 cup melted butter (cooled), 1 teaspoon vanilla, and 2 tablespoons fresh lemon juice. If using almond extract, add 1/4 teaspoon.
Bring the batter together. Pour the wet ingredients into the dry.
Stir gently with a spatula until just combined. The batter should be thick and a little lumpy. Do not overmix or the muffins will be tough.
Fill the cups. Divide the batter evenly among the 12 muffin cups, filling each about 3/4 full. For bigger domes, you can fill them slightly higher and make 10 muffins instead.
Bake with a temperature trick. Bake at 400°F for 5 minutes, then lower the oven to 350°F (175°C) and bake 10–12 more minutes, until the tops are golden and a toothpick comes out clean or with a few moist crumbs.
Cool briefly. Let muffins rest in the pan for 5 minutes, then transfer to a wire rack to cool.
This prevents soggy bottoms.
Glaze. Whisk 1 cup powdered sugar with 2–3 tablespoons fresh lemon juice until smooth and pourable. Drizzle over warm (not hot) muffins for a glossy finish.