Preheat the oven to 350°F (175°C).
Line a muffin tin (30 cavities) with paper boxes.
In a large bowl, beat 1 cup of butter with the sugar. Add eggs, one at a time, before adding lemon zest and 1 tsp vanilla; mix well.
In a separate bowl, combine flour, baking soda, baking powder and salt; gradually stir into the previous mixture, alternating with sour cream.
Transfer 4 tbsp of dough to each cavity of the mold.
Bake for 25-30 minutes, until a toothpick inserted in the center of the muffins comes out clean. Let cool for 10 minutes before transferring the muffins to a wire rack for complete cooling.