Preheat the oven to 180°C / 160°C fan / 350°F / Gas 4.
Line a 25 cm (10-inch) springform pan with baking parchment.
In a large mixing bowl, beat the softened butter and caster sugar until pale, light and fluffy.
Add the eggs one at a time, mixing until just combined after each addition.
Mix in the milk and vanilla.
Sift in the flour, baking powder, salt and cinnamon. Fold until just combined and smooth.
Spoon the batter into the prepared pan and level the surface.
Peel, halve and core the apples.
Thinly slice each apple half while keeping the slices together. Arrange the sliced halves over the batter and press them in by about 1 cm (½ inch).
Spoon the honey evenly over the apples. Warm it briefly if necessary so that it pours easily.
Bake for 45–50 minutes, until golden and a skewer inserted into the cake comes out clean.
Leave the cake to cool in the pan for 10 minutes.
Remove the outer ring and leave the cake to cool.
Serve warm or cold, lightly dusted with icing sugar.