Place flour, yeast, sugar, butter, egg, milk, vanilla and salt in a mixer bowl with a dough hook and knead at low speed for 10–12 minutes until you get a smooth dough.

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

Transfer the dough to a lightly floured work surface and roll out to a rectangle half a centimeter (one-quarter inch) thick. Brush the rectangle with a generous layer of soft butter.

Sprinkle with sugar and cinnamon in a uniform layer and dark chocolate over it.

Roll into a tight roll and cut into 12 roses.

Place each rose in the greased cup of a muffin pan, cover, and let rise for 30–60 minutes or until almost doubled.

Heat oven to 340 degrees Fahrenheit (170 degrees Celsius).

Gently brush the cinnamon rolls with a beaten egg.

Bake for 18–25 minutes or until the cinnamon rolls are golden and firm. Cool slightly at room temperature.

Melt the chocolate in the microwave or double boiler. Transfer to a small piping bag and pipe thin stripes on top of the cinnamon rolls.