• In a medium bowl, whisk the 2 extra-large eggs, 250 ml brown sugar, and 500 ml buttermilk until the sugar starts dissolving.
• Melt the 500 g margarine, then stir it into the buttermilk-egg mixture.
• In your largest mixing bowl, combine the 1 kg self-raising flour, 250 ml jungle oats, 250 ml coconut, 350 ml muesli, 50 ml sunflower seeds, 3 tsp baking powder, and a pinch of salt.
• Pour the wet mixture into the dry bowl and mix with a wooden spoon.
• When it gets heavy, switch to your hands and gently bring everything together. Don’t over-knead;  you’re just combining, not making bread.
• Press the dough into a 30×30 cm square baking pan (or similar large pan), patting it down to about 2.5–3 cm thick.
• Score the top into squares now; it makes breaking them easier later.
• Bake at 200°C (or 180°C fan) for 1 hour, until the top feels firm and lightly golden.
• Let the slab rest for 10 minutes, then turn it out carefully onto a wire rack.
• Let it cool completely; it breaks cleaner once cold.
• Break or cut along the score lines. Arrange the rusks on baking sheets in a single layer.
• Dry in the oven at 80°C for 6–7 hours or overnight.
• If your oven traps steam or runs hot at low temperatures, leave the door slightly open with a wooden spoon.
• Cool completely before storing.

Storage

1. Store in an airtight tin for up to 3 weeks.