Pre-heat the oven to 425° F. Line the inside of a 12-cup muffin pan with muffin liners or grease well with butter or oil.

Make the streusel topping by combing the flour, sugar, and lemon zest in a small bowl. Add the melted butter and using a fork, stir into large crumbs. Chill the mixture in the fridge until ready to use.

Combine the flour, baking powder, baking soda, and salt in a medium bowl and whisk together to break up any lumps.

In a separate bowl and using an electric mixer, beat the butter on medium speed for a minute or two. Add the sugar to the bowl and cream the butter and sugar together for 5 minutes until it is fluffy and light in color. Scrape down the bowl with a rubber spatula one or two times as needed. Beat in the lemon zest, egg, egg yolks, lemon extract, and sour cream until everything is blended.

Stir in the milk and lemon juice and then gradually add the dry ingredients to the wet and mix just until combined. Do not overmix.

Spoon the batter into the prepared muffin cups. Sprinkle the streusel topping evenly over the batter. Press the crumbs down slightly into the batter.

Transfer the muffin pan to a cooling rack and let it cool for 3 minutes. Then, remove the muffins from the muffin pan and place muffins directly on the cooking rack to cool completely.

To make the glaze, combine the powdered sugar, lemon zest and 2 teaspoons lemon juice. Whisk until smooth. Add additional lemon juice or water as needed to make a drizzling consistency.

Drizzle some lemon glaze on the cooled muffins. Store for 2 to 3 days in an air-tight container.