270 ml warm milk (about 110 °F/43 °C)

7 g (2 tsp) active dry yeast

3 tbsp granulated sugar

2 large eggs

1 tbsp baking powder

½ tsp fine salt

1 tbsp distilled white vinegar

700–750 g (5½–6 cups) all-purpose flour, plus extra for dusting

50 g (3.5 tbsp) unsalted butter, softened

1 tbsp vegetable oil, for greasing

1 ripe banana, thinly sliced

1 tbsp granulated sugar, for filling (or to taste)

40 g (3 tbsp) jam (currant or your choice)

Egg wash: 1 egg yolk + 1 tbsp milk, beaten together

30 g (3 tbsp) poppy seeds