Preheat the oven to 370°F.
Place the flour, sugar, chopped dates and baking powder into a large bowl, together with the walnuts, sunflowers and chia seeds. Mix together.
Mix the melted butter and beaten egg together and pour into the dry ingredients.
Pour in enough buttermilk to form a firm batter and pour into a lined 1 pound loaf tin.
Bake for 35 to 40 minutes. To check that the loaf is fully cooked, tap on the base, it should sound “hollow”. The top will crack a little. Place on a cooling rack.
To make the frosting, whisk together the smooth cream cheese and natural yoghurt with the icing sugar and vanilla extract until mixture well and smooth.
When the cake is cold, place on a tray or a board and spread the frosting on the top. Decorate with walnut halves and serve.