Heat the oven to 350°F (175°C). Lightly grease a 4-by-9-inch loaf pan with non-stick cooking spray or butter, and line it with parchment paper, leaving some overhang on both of the longer sides, so you’re able to easily lift the cake out after baking.
Prepare chia eggs by whisking two tablespoons of chia seeds with 5 tablespoons of water in a small bowl or mug. Set aside.
Whisk the flour, baking powder, salt and turmeric in a large bowl.
In a medium bowl, mix the zest and juice of one orange with sugar. Whisk in the chia eggs and melted coconut oil.
Using a spatula, add the wet mixture to the flour mixture, stirring just to blend. Scrape the batter into the prepared pan, smoothing the top. Scatter the top with pine nuts and 2 tablespoons of sugar. This is optional but highly recommended.
Bake until the top of the cake is golden brown, the edges pull away from the sides of the pan, and a toothpick inserted into the centre comes out clean, 50 to 60 minutes.
Remove the cake from the pan using overhanging parchment paper and transfer to a cooling rack. Let it cool a bit and serve warm, or cool completely and store in an airtight container at room temperature for up to 5 days.