Directions

1. Dissolve baking powder in milk in a small bowl. Whisk eggs with a mixer on high speed until very thick and pale, about 10 minutes. With machine running, slowly add sugar, beating until smooth and creamy. Add butter, 1 tablespoon at a time, beating after each addition. Beat in milk mixture, salt, anise extract, and lemon zest until just combined.
2. Reduce speed to medium-low. Add 6 cups flour, 1 cup at a time, mixing well after each addition. Remove bowl from mixer, and stir in remaining 3 cups flour, 1 cup at a time, until flour is incorporated and dough is stiff.
3. Transfer dough to a floured surface, and knead until dough is smooth and not sticky, adding more flour if necessary. Divide dough into 4 pieces, and wrap in plastic wrap.
4. Dust surface and springerle mold with confectioners' sugar. Roll out 1 disk of dough at a time to a 1/4- to 3/8-inch thickness (deeper molds will need thicker dough). Cut a piece of dough about the size of the mold. Press mold firmly into dough, flip over, and gently roll over dough with rolling pin. Flip over, and press onto a parchment-lined baking sheet. Using a knife, trim excess dough from sides of mold. Gently coax dough out of mold with fingertips and onto baking sheet. Repeat, spacing cookies 1 inch apart, and placing same-size cookies on same sheet. Let stand, uncovered, for 24 hours.
   
5. Preheat oven to 220 degrees. Bake cookies, 1 sheet at a time, until completely dry, about 1 hour. (They should not color; reduce oven temperature to 200 degrees if cookies start to color.) Let cookies cool on sheets on wire racks. Cookies will keep, unglazed and covered, for up to 2 to 3 weeks.
6. Make the glaze: Mix lemon extract and a pinch of luster or petal dust in a small bowl, adding more dust as needed to get desired color. (You will need only a little dust; the mixture should remain runny). Using a very fine paintbrush, brush the tinted extract onto the flat portion of each cookie around the relief. Using a clean, damp paintbrush, remove smudges. Mix additional extract and luster or petal dust in 1/2 teaspoon increments as needed.