Pre-heat oven 180°C. Butter and line round loose bottomed cake tin (approx. 20cm diameter) with parchment.
Whisk together flour, baking powder, cinnamon, sugar, butter and eggs in a bowl until mix is glossy and smooth.
Chop 2 of the apples roughly and fold into mix, adding extra liquid only if needed. The mixture should be a dropping consistency.
Spoon into prepared tin and level surface with a spatula.
Slice the remaining apple quarters, then slice and arrange segments in wheels radiating from the centre.
Bake for 25-30 minutes until risen, set and slightly shrunk at the edges. A skewer should come out clean when inserted into the middle of the cake. Cool on a wire tray.