Combine and whisk 5 cups of flour, sugar, salt, lemon zest, salt, and nutmeg in a large bowl.
In a separate bowl, combine the warm milk, yeast, and orange juice. Create a well in the center of the flour mixture, then pour the yeast mixture in the center.
Stir the mixture until it creates a shaggy dough. Add one tablespoon of butter at a time, making sure to full incorporate it before adding the next. Add a tablespoon of flour at a time if the dough is too wet, up to 1/2 cup.
Lightly oil a bowl, then place the dough ball in the bowl. Drape a damp kitchen towel over the bowl, then place the bowl in the fridge for 1 hour.
Preheat the oven to 350 degrees. Dump the dough out on a lightly floured surface. Flour your rolling pin, then stretch the dough into a 12X20 inch rectangle.
Combine the sugar and cinnamon in a small bowl, then sprinkle the sugar mixture on the dough, keeping the 1 inch edge of the dough clear.
Grab the long edge near you, then roll the dough into itself so it is rolled into a cylinder shape. Place the plastic baby randomly in the dough about mid way through rolling it.
Place the dough on a parchment paper lined baking sheet seam side down. Join the ends of the dough together, Wet your fingers and pinch the edges togeher.
Place the king cake in the oven on the middle rack and bake for 40 minutes.
Remove the king cake from the oven and allow it to cool for 30 minutes. Combine the confectioner's sugar, vanilla extract, and water. Mix until it is a glaze.
Glaze the king cake with the icing using a spoon, then decorate the cake with the green, gold, and purple spinkles. Cut, serve, mangia!