Step 1

Process granulated sugar, rosemary, and lavender buds in a food processor until rosemary and lavender are finely chopped, about 1 minute.

Step 2

Beat butter on medium speed with a heavy-duty electric stand mixer until creamy. Gradually add sugar mixture, beating until smooth.

Step 3

Stir together flour, baking powder, and salt in a medium bowl. Gradually add flour mixture to butter mixture, beating on low speed just until blended.

Step 4

Shape dough into 2 (8-inch) logs. Roll each log in 1 tablespoon of the demerara sugar. Wrap each log in wax paper, and chill 3 hours.

Step 5

Preheat oven to 350°F. Cut each log into 24 slices. Place slices 1 inch apart on baking sheets lined with parchment paper. Bake in preheated oven until edges of slices are golden, 10 to 12 minutes.

Step 6

Transfer cookies to wire racks, and cool completely, about 20 minutes. Store in airtight containers.