Warm the milk to between 100 to 110 degrees F (usually 30 seconds in the microwave does the trick!) and pour into a mixing bowl. Sprinkle the yeast over top and let sit for 5 to 10 minutes, until foamy.
Add the sugar, butter, eggs, and vanilla extract, and stir to combine.
Add the flour and the salt and stir with a wooden spoon until a shaggy dough forms. Add the golden raisins then, using the dough hook, knead on medium-low speed until a smooth, shiny ball of dough is formed, 3 to 6 minutes, adding additional flour as necessary. (You can also knead by hand until smooth ball is formed.) Place the dough in a greased bowl and cover with plastic wrap. Place in a warm, draft-free spot until doubled in size, 1 to 2 hours (rise time will depend on temperature and humidity in your kitchen).
Punch dough down and remove from the bowl to a clean work area. Remove one-quarter of the dough and set aside. Form the large piece of dough into a ball and place in a 9-inch round cake pan or springform pan.
Divide the remaining piece of dough into three pieces and roll them each out into a 20-inch strand. Braid the three strands together for one long braid. Divide the braid in half and use it to form a cross over the top of the large ball of dough in the pan. (Alternately, you can wrap the braid in one length around the inside edge of the pan.)
Cover lightly with plastic wrap and let rise until puffy and nearly doubled in size, 45 to 60 minutes.
Preheat oven to 400 degrees F.
Whisk together the egg and water, then brush evenly all over the top of the dough and sprinkle with sugar, if desired.
Bake for 15 minutes, then reduce the oven temperature to 350 degrees F and bake for an additional 25 to 30 minutes, until golden brown and an instant-read thermometer registers 190 degrees F. You can tent the pan with aluminum foil if it is browning too quickly. Remove from the oven, turn the bread out of the pan, and place it on a wire rack to cool completely.