• 225 g (8 oz/1 cup) coconut oil, plus extra for greasing
• 200 g (7 oz) dark 70% chocolate, chopped
• 3 tablespoons cacao powder, plus extra for dusting
• 125 ml (4 fl oz/½ cup) maple syrup
• 80 ml (2½ fl oz/¼ cup) agave syrup or mild honey
• 1 teaspoon natural vanilla extract
• 3 eggs, lightly beaten
• ¼ teaspoon salt
• 150 g (5½ oz/1 cup) wholemeal (whole-wheat) plain (all-purpose) flour
• 1 teaspoon baking powder
• 3 tablespoons coarsely chopped walnuts
• 75 g (2¾ oz) good-quality milk chocolate, cut into 1 cm (½ inch) pieces

Grease the slow cooker and line with baking paper. Melt the coconut oil and dark chocolate in a heatproof bowl set over a saucepan of barely simmering water.

Once melted, stir in the cacao powder, maple syrup, agave syrup, vanilla, eggs and salt. Fold in the flour and baking powder until just combined, then stir in the walnuts and milk chocolate.

Pour into the slow cooker (see Tip) and cook on low for 2½ hours or until cooked through when you poke a skewer into the centre and a few crumbs stick. Turn off the slow cooker, leaving the brownie inside for 20 minutes, then remove to prevent the brownie overcooking.

Use the baking paper to gently lift out the brownie and cut it into pieces. Dust with cacao powder to serve.