Lightly spray a 13 x 9-inch/33 x 23 cm pan with non-stick spray.
Add 4 cups of flour, sugar, yeast and salt in a large bowl (use stand mixer bowl if using stand mixer); whisk to combine.
If using a stand mixer, attach the dough hook and use the mixer bowl for the dry ingredients. In a separate bowl, whisk together the water, oil, eggs and egg yolk. With the mixer running, slowly add the water mixture. Let the machine knead the dough for 7-8 minutes. If the dough is sticking, add up to 1/4 cup of additional flour.
If mixing by hand, slowly add the water mixture until a soft dough forms. If dough is too sticky, add up to 1/4 cup more flour. Knead for 7-8 minutes.
Remove the dough from the bowl and lightly spray the entire bowl with non-stick spray. Return the dough to the bowl and cover tightly with plastic wrap and let rise in a warm place for about 1 1/2 hours, or until doubled in bulk.
To make the filling, mix all filling ingredients thoroughly. Set aside.
Roll out the dough to a 24 x 10-inch/61 x 24-cm rectangle. Spread half the filling over the entire rectangle. Roll up tightly from the long side, seal seam and cut into 15 equal portions.
Place the rolls in the prepared pan, 3 across and 5 down. Cover and let rise for 30 minutes.
Preheat oven to 350F/180C. Bake rolls for 30-35 minutes, until golden brown.
Remove from oven and immediately spread remaining filling over the rolls.