Preheat the oven to 170°C/325°F/gas mark 3. Lightly grease and line a 900g loaf tin with baking parchment.
In a bowl, beat together the sugar and egg yolks until fluffy, pale and creamy. Add the grated pumpkin, along with the orange zest and
juice, vanilla, walnuts and apricots. Sift the flour, salt and spices and fold into the mixture, along with the ground almonds, moving the
spoon in a figure-of-eight movement.
In a clean, dry bowl, beat the egg whites until they form soft peaks, then fold gently into the pumpkin mixture. Do not beat or overmix.
Spoon the mixture into the lined tin and bake for 50–60 minutes, or until well risen and golden brown. You can check whether the cake is cooked by inserting a thin skewer into the middle – it should come out clean. Leave to cool in the tin for 5 minutes, then turn out and cool completely on a wire rack.
To make the orange drizzle, mix the icing sugar and orange juice together in a bowl until smooth. Drizzle over the top of the loaf and then scatter over the orange zest. Leave to set.
Cut into slices to serve. The loaf will keep well in an airtight container in the fridge for up to 5 days, or in a cool place for 2–3 days.