For the doughnuts

1 cup lukewarm milk
1/4 cup lukewarm water
3 Tbsp caster sugar
4 tsp instant dried yeast
100g butter, melted and cooled
3 eggs
4 1/4 cups plain flour
Vegetable oil for frying
1/2 cup sugar + 2 tsp cinnamon to coat

For the filling

250ml milk
250ml cream
1 tsp vanilla essence
1/2 cup caster sugar
3 egg yolks
1/4 cup cornflour
2 ripe Dole bananas, mashed

For the Caramel

1 cup sugar
85g butter, cubed
1/2 cup cream
1 tsp vanilla extract
1/2 tsp sea salt plus extra to garnish

1. To make the doughnuts, put milk, water, sugar and yeast in the bowl of a stand mixer and whisk to combine. Leave to stand for 5 minutes or until frothy.
2. Mix together butter and eggs and add to the yeast mix. Add flour and mix with a dough hook until a sticky dough forms, then mix for a further 5 minutes until the dough is smooth and elastic.
3. Roll out the dough on a lightly floured surface to about 1.5cm thick. Using an 8cm round cookie cutter, cut rounds from the dough and place on baking trays lined with baking paper. Cover with a clean, dry teatowel and leave to rise in a warm place – until doubled in size (about 30 minutes).
4. Heat the oil in a large saucepan over medium heat. Cook the doughnuts a few at a time for 1 minute each side or until golden. Drain briefly on paper towels then roll in cinnamon sugar.
5. To make the filling, heat the milk, cream, vanilla and half the sugar in a saucepan over low heat. Meanwhile, whisk the egg yolks, remaining sugar and cornflour in a bowl until pale and thick. Just before the milk begins to boil, remove from heat and pour about half of it into the egg mix while whisking constantly. Return the pan of milk to the heat and pour the egg mixture into the milk. Keep whisking the mix until it nearly comes back to the boil and thickens. Immediately pour into a clean bowl, mix through mashed banana, cover and refrigerate.
6. To make the caramel, heat the sugar in a pot over medium-high heat, stirring with a wooden spoon. When it has melted and turned a golden amber colour, add butter and whisk until combined. Drizzle in the cream slowly, whisking constantly until fully combined. This could take about 2-3 minutes. Remove from the heat and stir in vanilla and salt.
7. To assemble, poke a hole in the side of each doughnut with a chopstick or similar to create a cavity. Fill a piping bag with the banana crème and gently fill each doughnut until you feel it expanding slightly. Spoon over caramel sauce and top with a little extra sea salt for garnish.