Preheat the oven to 375°F. Add muffin liners to a 12-cup muffin tin.
In a large bowl, combine the all-purpose flour, granulated sugar, poppy seeds, baking powder, and baking soda with a mixing spoon.
In another large bowl, whisk together the whole milk yogurt, lemon juice, lemon zest, and eggs.
Pour the wet ingredients in with the dry ingredients, then mix. Pour the melted butter into the bowl and fold until just combined.
Using a large cookie scoop, divide the batter equally amongst the lined muffin tin. Place the muffin tin on the middle oven row and bake for 25 minutes.
Once the muffins finish baking, start on the lemon syrup. Add the lemon juice and granulated sugar to a saucepan and stir over medium heat. The mixture should bubble up and thicken after about 5 minutes.
Brush the tops of the muffins generously with the lemon syrup, then sprinkle 1 or 2 pinches of coarse sugar over each muffin.