Make the streusel

1. In a small mixing bowl, mix the flour and salt. Set it aside.
2. In a medium mixing bowl, pour in the melted butter and sugar. Use a fork to gently mix and fluff together until a moist crumble texture forms. Cover it with plastic wrap or a lid and place into fridge until needed.

Make the muffin batter

1. Preheat the over to 220℃/425℉ and a cupcake pan with 7 tulip muffin cases.
2. Add the zest of a lemon into the brown sugar. Use the fingertips to rub the sugar and zest of lemon. It helps release the natural lemon oil.
3. In a large mixing bowl, mix in the melted butter and milk using a whisk until they are emulsified.
4. Add in the eggs, vanilla extract and lemon extract. Whisk them well.
5. Combine the yogurt and lemon juice for extra citrusy flavour and the sugar zest mixture. Continue to whisk until everything is well mixed.
6. Place a sift on top of the mixing bowl, add the all purpose flour, baking powder, baking soda and salt. Sifting the dry ingredients help break up clumps for easy mixing. Gently fold together until just combined, do not over mix the batter.
7. Sprinkle the poppy seeds into the batter. Fold them in gently until the seeds are evenly incorporated.
8. Fill the liners most of the way with batter using the ice-cream scoop. Cover the batter with the chilled streusel topping.
9. Bake the muffins in the preheated oven at 220℃/425℉ for 5 minutes. Then lower the temperature to 180℃/350℉ and continue to bake them for another 15 to 18 minutes or until golden brown and cooked through.
10. Once the muffins are done, remove them from the oven and let them sit in the pan for a few minutes. When you can handle them, transfer them onto a wire rack to cool down completely.
11. Enjoy them when they are still warm with a cup of coffee!