Break chocolate and place in heatproof bowl. Add coconut oil, dates, cranberries, salt and orange zest. Sit over a pan (bain-marie) of gently simmering water to melt the chocolate, stirring occasionally. Remove from heat and allow to cool slightly.
Whilst chocolate is melting, heat a heavy pan over medium heat. Add the nuts and gently stir for about 3-5 minutes until fragrant. Transfer to a large bowl to cool.
Repeat with the seeds, which need less time, approx. 1-2 minutes. They also release a toasty fragrance, and the sesame seeds will start popping. Once toasted, mix in with the nuts.
Important - nuts and seeds burn easily, so keep stirring while they are toasting.
Add 90 percent of the nuts and seeds to the chocolate bowl. Stir to combine then pour into the parchment lined baking tray, pressing the mixture into the tin firmly. Top with remaining nuts and seeds and press down again with the back of a spoon. Chill in the fridge for 2 hours to set, then cut into small squares. Store in airtight container in fridge for up to one month or freeze for up to 3 months.