Preheat the oven to 350F. Line a muffin pan with paper or silicone muffin liners, or grease the muffin pan.
In a large bowl, whisk together the wet ingredients: melted butter, honey, eggs, yogurt, the zest and juice from one lemon, and vanilla extract.
Add the dry ingredients to the bowl (flour, baking powder, baking soda, and salt), and stir to combine. Finally, stir in the poppy seeds.
If you're using the optional sugar topping, place the lemon zest and sugar in a small bowl. Massage the two ingredients together for a few seconds. Set aside.
Scoop the batter into the muffin pan (it will be thick). I use an ice scooper. If you're using the sugar topping (previous optional step), sprinkle the sugar evenly over the muffins before baking.
Bake the muffins for 18-20 minutes, until firm on top. My muffins are usually done at 18 minutes, but this may vary with each oven. Allow the muffins to cool for a few minutes before enjoying.
For storage, I keep the muffins in an air-tight container in the fridge (they will need to be warmed, in my opinion, before enjoying). They also freeze well.