• Preheat the oven to 400°F (200°C). Add paper liners to a 12-cup muffin pan.

Make the Lemon Streusel

• Melt the butter over low heat and as soon as it’s almost completely melted take it off the heat. Whisk together the flour, sugar, and salt in a small bowl. Zest the lemon directly into the dry ingredients.
• Use your fingers to rub the zest into the dry ingredients. Add the melted butter to the dry ingredients and use a fork to work the butter into the dry ingredients until there are no bits of white flour left, and the streusel forms clumps.
• Place it in the refrigerator while you make the muffin batter.

Make the Lemon Muffin Batter

• Melt the butter over medium low heat and cool until it is barely warm, about 90 degrees F. Crack the eggs into a small bowl.
• Place the all-purpose flour, baking powder, baking soda, poppy seeds, and salt in a bowl and whisk for 30 seconds to combine.
• Place the sugar in a large bowl. Zest the lemons into the same bowl on top of the sugar until you have what appears to be 2 tablespoons. Use your fingers to rub the lemon zest into the sugar, until the sugar turns yellow and has a sandy texture.
• Add the eggs to the lemon sugar mixture and whisk for about 1 minute until the eggs are thoroughly combined and it's lighter in color. Whisk in the cool melted butter. Next whisk in the sour cream, lemon juice, and vanilla extract. Let the batter sit for about 5 minutes.
• Add 1/2 of the dry ingredients to the batter and fold it with a silicone spatula until incorporated. Add the remaining dry ingredients and mix on low speed until combined. Scrape the sides and bottom of the bowl to ensure all the ingredients are thoroughly combined. The batter should be lumpy.

Bake the Muffins

• Divide the batter even between the 12 muffin cups (about 69 grams per muffin tin). The muffin cups should be about 3/4 full. Sprinkle about 1 tablespoon of lemon streusel over each muffin.
• Bake the muffins at 400°F for 5 minutes and then without opening the oven door reduce the temperature to 350°F. Bake the muffins for another 12-14 minutes until the internal temperature registers at about 200°F using an instant-read thermometer.
• Remove the muffins from the oven and place the muffin tin on a wire cooling rack. Cool the muffins in the pan for 5 minutes, then move the muffins to the cooling rack.
• The muffins taste fantastic but if you like a little lemon glaze I've given you the perfect recipe.

Storing the Muffins

• Room Temperature. Cool the muffins completely and then place them in an airtight container. Store the muffins for up to 3 days.

  Refrigerator. Store the muffins in an airtight container for up to 7 days. Bring them to room temperature before eating or warm the muffins in the microwave for about 10-15 seconds.
• See the directions in the Recipe Notes for freezing the muffins.