CRUMBLE TOPPING
In a small bowl, combine flour, and sugar. Pour in melted butter,lemon extract, lemon juice and zest, and mix with a fork until crumbles form. Chill in the refrigerator while you make the muffin batter.
MUFFINS
In a large bowl, combine the flour, baking powder, salt, poppy seeds, and sugar in a large mixing bowl, making a well in the center.
In a small bowl, add the beaten egg, lemon extract, lemon juice, lemon zest milk, and oil and whisk together
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix, or your muffins will be tough.
Cover with plastic wrap and put in the refrigerator for an hour or longer. You can skip this step, but the longer they are refrigerated, the more flavorful they'll be
Preheat your oven to 425 degrees; line tins with cupcake liners or grease the cups lightly.
Pour batter into every other muffin tin and fill the remaining empty tins with 1/2 inch water.
Sprinkle the crumb topping evenly over the muffin batter in each cup.
Bake the muffins at 425 for 5 minutes, and then lower the temperature to 350 and cook another 10-12 minutes or until a toothpick comes out clean in the middle.
Transfer to a wire rack, allow the muffins to cool for 30 minutes, and then drizzle glaze on top.
GLAZE
Mix powdered sugar and milk, whisk together, then pour over the top. If you want a thicker glaze, add less milk.