In a mixer bowl with a dough hook, put flour, yeast, sugar, oil, milk, and salt and knead for 10–12 minutes until a smooth dough is obtained.

Cover the bowl and let the dough rise for one to two hours or until it doubles in volume.

Break the chocolate into squares and place in a bowl.

Add butter and melt together in a microwave oven or double boiler until everything is melted and the mixture is smooth.

Cool the mixture at room temperature until it reaches a spreadable texture.

Transfer the dough to a lightly floured work surface and divide into two parts.

Roll out each part till 1/2-centimeter (1/4-inch) thick rectangle. Spread half of the filling over each part, evenly spread half the banana cubes, and roll tightly.

Cut the roll lengthwise (so the filling can be seen) and form a screw shape from the two parts.

Place the cake in a greased baking pan and repeat with the other half of the dough, the rest of the filling and the banana and the second baking pan.

Cover the pans and let rise for about an hour or until almost doubled.

Heat oven to 170 degrees (340 degrees Fahrenheit).

Brush the risen cakes gently with a beaten egg.

Bake for 30–40 minutes or until the cakes are golden and firm to the touch. Cool completely at room temperature.

In a small pot, place water and sugar and heat on a high flame until all the sugar is melted and a boiling syrup is obtained.

Brush the cooled cakes generously with the hot syrup.