Preheat the oven to 175 C, 10 mins before baking. Grease a 9 inch loaf tin, with butter and dust with flour.
Using a handheld electric whisk or a freestanding electric mixer with the paddle attachment, cream together the butter, orange zest and sugar until the mixture is soft and fluffy. Add the eggs one at a time, whisking well after each addition. Scrape down the sides of the bowl, every now and then to ensure the eggs and butter are properly mixed in.
In a separate bowl, mix together the flour, ground almonds, baking powder and salt. Tip the dry ingredients into the creamed mixture in two batches and whisk together on a low speed until just incorporated, then mix in the yoghurt and vanilla essence.
Pour the batter into the prepared loaf tin and sprinkle the flaked almonds on top. Place in the oven and bake for 50-60 mins (refer notes) or until the sponge is firm on top and a skewer inserted into the centre of the cake comes out clean.
Remove from the oven and allow the loaf to cool, a little before turning it out of the tin on to a wire rack to cool completely for serving.
Notes
For cup measurements, please check out this link.You can store the cake at room temp for 2-3 days. This cake tends to dry out easily, so make sure you wrap it nicely in a cling film and store it.I used 2 oranges to get the reqd quantity of the zest. My cake was ready in 40-45 mins.caster sugar substitute - Just pulse normal sugar in a grinder for a few seconds, make sure you dont powder it. I used store bought almond meal, to make ground almonds at home, please check out this link.Make sure you sprinkle extra flakes on top of the cake (especially center portion), since it spreads out during baking.