In a large mixing bowl, combine 1 1/2 cups flour with the yeast and cinnamon.
Heat milk, vegetable oil, sugar, and salt in a saucepan until warm; stir constantly. Remove from heat and beat for 3 minutes at high speed. Add all at once to the flour mixture, along with the eggs. Beat at low speed for 1 minute, scraping sides of bowl constantly. Beat 3 more minutes at high speed. Stir in currants and as much of remaining flour as possible.
Turn dough out onto a lightly floured surface and knead in enough of remaining flour to make a moderately soft dough that is smooth and elastic. Shape into a ball. Place in a lightly greased bowl, turning once to coat surface. Cover with a towel and place in a warm spot. Let rise until double, about 1 1/2 hours.
Punch dough down and turn out onto lightly floured surface. Cover and let rest for 10 minutes.
Divide dough into 18 pieces and form each into a smooth ball. Place on a greased baking sheet 1 1/2 inches apart. Cover; let rise until nearly double (30 to 45 minutes).
With a sharp knife, cut a cross (to represent either the cross of Christ, the sun, or the combination of male and female energies) onto each. Brush tops of each bun with some of the slightly beaten egg white (reserve remaining white).
Bake at 375 degrees for 12 to 15 minutes or until golden. Cool slightly.
Meanwhile, combine powdered sugar, vanilla, dash of salt, and the reserved egg white. Add more milk if necessary to give it piping consistency. Pipe crosses on top of buns with a pastry decorator.