Butter and line with parchment a 9x5-inch (12½ x 23 cm) loaf pan. Set aside.
In a small saucepan over medium heat (or using a microwave with a microwave-safe bowl), heat the water, milk, butter and raisins until the butter has melted and the liquid is beginning to simmer. Cover and set aside to let cool to lukewarm while allowing the raisins to plump up, about 20 minutes.
In the bowl of a stand mixer fitted with a dough hook (please see tips if kneading by hand), mix together the flour, yeast, and salt.
Whisk the egg into the cooled wet ingredients, then add into the dry and mix on medium-low speed for about 8 minutes.
Roll dough into a smooth ball and place in a large, oiled mixing bowl, turning the dough in the bowl to coat with oil. Cover the bowl with plastic wrap (or a shower cap) and clean towel and allow to rise in a warm place for roughly 60-90 minutes, or until doubled in size.
Once proofed, roll the dough on a lightly floured surface into a 9x18 inch (23x46 cm) rectangle.
Make the Cinnamon Swirl: In a small bowl, combine the sugar and cinnamon, then sprinkle this evenly all over the surface of the dough.
Starting at the long side, roll up the dough and place it, seam side down, into your prepared loaf pan. Cover with plastic wrap or a clean tea towel and let rise in a warm place until doubled, about 45-60 minutes.
Towards the end of the rising time, preheat the oven to 400°F (200°C).
Carefully brush the loaf with egg wash and bake for 35-40 minutes or until golden brown.
Let cool for 10 minutes in the pan, then transfer to a wire rack to cool completely before slicing. Store bread in an airtight container at room temperature for up to 4 days, or freeze for up to 2 months.