Thoroughly grease the bundt tin with butter and dust with ground almonds ensuring no areas have been missed. Preheat a warming drawer to 28C/82F (if you don’t have a warming drawer you can prove the dough by a sunny window or suspended over a bowl of hot water).
For the dough, place a heatproof bowl over a pan of gently simmering water. Add the milk and 25ml/1fl oz water to the bowl and warm it gently until it reaches 45C/113F on a cook’s thermometer.
Meanwhile, in the bowl of a freestanding mixer, cream together the caster sugar and softened butter until pale and fluffy. Add the flour, cinnamon, salt, lemon zest and instant yeast, making sure the yeast doesn’t touch the salt.
Add the warm milk mixture and eggs. Slowly mix using the paddle attachment to bring the mixture together, then increase the speed to medium and continue to mix for five minutes. The dough will be really sticky and stringy.
Fold in the diced apples and sultanas, then transfer the dough to the prepared tin. Shake the tin to make sure the dough is in all the nooks and crannies. Cover with a large piece of cling film (or a shower cap) and place in the warming drawer for 1hr 10 minutes, or until the dough has doubled in size and nearly reaches the top of the tin.
Preheat the oven to 190C/375F/Gas 5. Place a rack on the third shelf of the oven.
For the honeyed apples, melt 40g/1½oz of the butter in a large frying pan. Add the calvados, cinnamon, vanilla, honey, lemon juice and 120ml/4fl oz water and bring to the boil over a medium heat.
Stir in the apples and reduce the heat. Stir often and cook for about eight minutes, or until the apples are tender and the liquid has thickened. Remove from heat and stir in the remaining butter. Transfer to a bowl and set aside to cool.
When the cake has finished proving, bake for 35–40 minutes. Check it after 30 minutes, it is ready when a skewer placed in the centre comes out clean and the cake has come away from the sides of the tin slightly. Remove the cake from the oven and set aside to cool in the tin for about five minutes.
To decorate, put the blanched almonds on a baking tray and roast in the oven until golden-brown.
Turn out the cake into the centre of a serving plate and allow to cool for five minutes.
Prick the top of the cake with a skewer and drizzle over some of the sauce from the honeyed apples.
Decorate the cake with the roasted almonds. Place on a serving platter and spoon the honeyed apples in and around the cake. Drizzle any remaining sauce from the honeyed apples over the cake and serve.