Preheat the oven to 180°C/350°F. Line two 22-23cm round cake tins with baking paper, or one large bundt tin.
Using an electric mixer, beat the eggs and sugar until light and fluffy, about 4 minutes. Add the oil and spices (cinnamon, cloves, nutmeg) and continue beating until combined.
Sift together the flour, salt, baking powder, and bicarbonate of soda. Add to the egg mixture and beat until just incorporated. Remove from the mixer.
Fold the grated pumpkin, carrot, apple, and apricots (if using) through the batter by hand, ensuring everything is evenly mixed.
Divide the batter between the two prepared tins and bake for 50-60 minutes, until the cakes are firm and springy to the touch. A skewer inserted into the centre should come out clean.
If the top of the cake browns too quickly, loosely cover with foil and continue baking.
Allow the cakes to cool completely on a wire rack before removing from the tins.
To make the frosting, beat the butter, maple syrup, and icing sugar with an electric mixer until well combined and fluffy, about 3 minutes. Add the cream cheese and beat briefly until just combined. Do not overmix or the frosting will become too soft.
Place one cake layer on a serving plate. Spread a layer of frosting over the top, then place the second layer on top. Frost the top and sides of the cake.
Decorate with chopped walnuts. Refrigerate if not serving immediately.