1. Preheat oven to 350°F (175°C).
2. Grease or line an 11×17×1-inch pan with parchment (trim the paper to fit).
3. Place a rack in the middle of the oven.
4. Put butter in a heatproof bowl.
5. Pour boiling water over it to melt, stir in oil, and let the mixture cool for 2–3 minutes so it’s warm but not scalding.
6. This helps the dough come together without cooking the flour.
7. In a large bowl sift together the all-purpose flour, baking powder, and salt.
8. Add the whole wheat flour, rolled oats, granola, coconut, mixed dried fruit, sunflower and pumpkin seeds, brown sugar, and white sugar. Toss so the dry mix is uniform.
9. Make a well in the dry mix and pour in the warm butter-oil liquid.
10. Stir with a wooden spoon until just combined. The dough will be thick and slightly sticky; don’t overmix. If it feels dry, add 1–2 tbsp water; if too wet, add a tablespoon of flour.
11. Transfer to the prepared pan and press evenly.
12. Wet your hands with cold water and smooth the top.
13. Pre-score the top into rectangles with a knife dipped in boiled water (this gives cleaner edges).
14. Bake at 350°F for 40 minutes, rotating the pan once halfway if your oven browns unevenly.
15. The top should be golden and cracked.
16. Remove from oven and re-cut along the lines while the rusks are warm; this makes separation easier later. Let the pan cool completely on a rack.
17. Once cool, separate the rusks and arrange them on two large baking sheets or place them directly on the oven racks (use sheet on lower rack for crumbs).
18. Lower oven to 225°F (110°C). Prop the oven door open (place a spoon in the door) about 1–2 inches to let moisture escape.
19. Dry the rusks for 3–4 hours, flipping or rotating trays every 45–60 minutes for even drying.
20. They’re done when they snap cleanly and feel fully dry.
21. Cool completely, then store in an airtight container at room temperature for up to 2–3 weeks.
22. To freeze: place in a freezer bag for up to 3 months

Quick troubleshooting

• If rusks are chewy, dry longer at 225°F, or let them cool longer.
• If rusks crumble too much: try pressing a bit firmer into the pan next time or add one beaten egg to improve binding (optional; will make texture slightly cakier).