Preheat oven to 180C/350F (standard) or 160C/320F (fan/convection). Grease a 20 cm / 8” cake pan with butter.
Place Wet ingredients in a bowl. Whisk until combined.
Sprinkle over flour, baking powder and salt. Whisk until smooth - few small lumps is ok.
Pour into pan - it should be fairly thick but pourable (see video). Bake for 50 minutes or until a skewer comes out clean.
Remove metal ring and cool on rack then glaze.
Place ingredients in a bowl and whisk until smooth. Test down the side of the bowl to get the right thickness, using 1 tsp of yoghurt at a time to thin it out if required. Glaze should drip (slowly, because it's thick) but not be see through.
Place rack on a tray or baking paper.
Pour glaze over the middle of the cake, gently push towards the edges so it drips down the sides.
Let it set for 1 hour before transferring to a serving plate.
See note for how I did the lemon slices in the photos, and the alternative quick Cream Cheese Frosting.
