Step 1: Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.
Step 2: In a large mixing bowl, sift together the all-purpose flour, baking powder, baking soda, ground anise, and coarsely ground fennel seeds. Add the nigella seeds and mix well.
Step 3: In a separate bowl, whisk together the melted and cooled butter, granulated sugar, egg, milk, and white vinegar until well combined.
Step 4: Gradually add the wet mixture to the dry ingredients, mixing gently until it forms a soft dough.
Step 5: Using a tablespoon or cookie scoop, portion out the dough and shape it into balls. Place them on the prepared baking sheets.
Step 6: If using, sprinkle sesame seeds on top of each cookie before baking.
Step 7: Bake the cookies for 12-15 minutes, or until the edges are lightly golden brown.
Step 8: Once baked, let them cool on the baking sheet for a few minutes before transferring to a wire rack.
Notes
Store leftovers in an airtight container at room temperature for up to a week. They can also be frozen for up to three months.