Put flour, yeast, sugar, butter, egg, milk, vanilla, and salt into mixer bowl. Knead with dough hook on low speed for 10–12 minutes, until smooth dough forms.

Cover dough and let rise in a warm place for one to two hours, until doubled in size.

Break dark chocolate into cubes and put into a bowl. Add butter and melt in microwave or on double boiler, until completely melted and smooth.

Refrigerate about one hour, stirring occasionally, until a spreadable consistency is achieved.

Transfer risen dough to lightly floured work surface and roll into a 1/5-inch- (five-millimeter-) thick rectangle.

Spread chocolate evenly on dough.

Chop milk chocolate and white chocolate into small pieces and sprinkle evenly over bittersweet chocolate layer.

Roll up tightly jelly-roll-style and cut lengthwise to form two strips. Twist strips together (to form a screw) and place in a greased Bundt pan.

Cover and let rise for one hour in a warm place until cake almost doubles in size.

Heat oven to 350 degrees Fahrenheit (180 degrees Celsius).

Brush dough gently with beaten egg. Bake 35–45 minutes or until cake has risen and is golden and firm. Cool a bit at room temperature.

Bring sugar and water to a boil in a small saucepan. Once it boils, cook additional one to two minutes. Remove from fire.

Liberally brush cake with glaze and serve.