Preheat oven to 375°F (190°C). Line a 12-cup muffin pan with paper liners or grease lightly.
Prepare the streusel topping: In a small bowl, mix 1/4 cup flour, 2 tbsp sugar, and 1 tbsp butter. Rub together with your fingers until crumbly. Set aside.
In a large bowl, whisk together eggs, oil, sugar, and lemon zest until smooth. Stir in lemon extract (if using), buttermilk, and lemon juice.
Sprinkle in baking powder, baking soda, and salt. Gently fold in flour until just combined—do not overmix.
Divide batter evenly among muffin cups, filling each about 3/4 full. Sprinkle streusel topping over each muffin.
Bake for 20-23 minutes, or until a toothpick inserted into the center comes out clean.
Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
Enjoy warm or store in an airtight container for up to 3 days. Muffins can also be frozen for up to 3 months.