Line a baking tray with parchment. Lightly spray with cooking spray.
In a microwave-safe bowl, combine milk and water and microwave in 30-second increments until the mixture is warmed (110°F approx.)
Add flour, sugar, yeast, and salt into the bowl of a stand mixer fitted with the hook (bread paddle) attachment. Make a well in the center and add the warmed milk mixture, egg and melted butter to the well; mix on medium speed until incorporated. Increase the speed to medium-high and mix until the dough forms a ball and pulls away from the bowl's sides, about 8 - 10 minutes. The dough should be elastic but not sticky; if too sticky, add a little more flour, about a tablespoon at a time.
Place the dough on a lightly floured surface and form a ball. Place the dough ball in a lightly greased bowl. Cover and let it rise in a warm place until puffy and doubled in size, about 1-2 hours.
After the dough has risen, place it on a lightly floured surface and roll it into a 23-x-20 inch (60-x-50 cm) rectangle, about ½ inch (1.5 cm) thick. NOTE: This a big pan de jamon, if you prefer, divide the dough into 2 equal portions and make two smaller breads.
Arrange a row of whole olives on the upper edge. Slice the rest of the olives. Note: you can see step-by-step photos in the post content above.
Line the dough with the ham slices, slightly overlapping each piece and covering the dough's entire surface.
Sprinkle the raisins and sliced olives on top of the ham, scattering them evenly throughout. Drizzle with papelon syrup, if using.
Firmly roll it up like a Swiss roll. Transfer the roll, seam-side down, to the prepared baking sheet. Cover loosely with a damp towel. Place it in a warm and humid area in your kitchen, and let it rest for 60 minutes.
Preheat oven to 350º F (180º C).
Brush bread with egg wash on all sides. Bake for 40 – 45 minutes, or until golden brown. Remove the bread from the oven, and while is still hot brush wit ith melted butter.
Let the bread cool for 15 – 20 minutes before serving.