Preheat oven to 350°F (175°C). Whisk flour, baking soda, salt, rosemary and spices. Stir in fruit, nuts and seeds.
Stir in buttermilk, honey and optional zest until combined. The batter will be loose!
Divide among four greased 6 × 3 × 2-inch mini loaf pans. Bake 20–25 minutes until set and a toothpick comes out clean.
Rest in pans 5–10 minutes, then cool completely on a wire rack. Wrap tightly and freeze 1–2 hours until firm enough to slice. (Can be kept frozen at the point, if desired, to be sliced and baked at a later date.)
Using a sharp serrated knife, slice as thinly as possible, about ⅛ inch (3 mm).
Arrange slices directly on an oven-safe wire rack. Bake at 300°F (150°C) for 20–30 minutes until golden and crisp. No flipping needed! Cool completely before storing airtight.
