Step 1

Grease 5 medium-sized bowls and set aside.

Step 2

In a small, microwave-safe bowl, whisk together the milk and egg yolk. Microwave 30 seconds, and set aside.

Step 3

In a large bowl, combine the flour, sugar and yeast. Add the milk mixture, as well as the butter and salt and stir to combine.

Step 4

Using a dough hook on a stand mixer, or just your hands, knead the dough (5 minutes with a mixer, 10 minutes by hand) until the dough is smooth and elastic.

Step 5

Divide the dough into 5 equal portions.

Step 6

Working with one ball of dough at a time, dye each ball into one color of the rainbow - red, orange, yellow, green, blue, and purple. Add 5-10 drops of food coloring, knead until fully dyed and then place the dyed ball of dough in it's own individual, greased bowl. Repeat with all of the dough.

Step 7

Cover the bowls with a tea towel and let rise for 2 hours.

Step 8

Grease a loaf pan and line with parchment paper. Set aside.

Step 9

The dough should be at least doubled in size when the tea towel is removed.

Step 10

Punch the dough down and then remove from the bowl.

Step 11

You can shape the dough into a log a couple of different ways: you can roll out the dough to equal-sized rectangles and then lay each layer on top of each other, then roll into a large log/loaf; OR, roll the purple dough into a log shape, then roll the other doughs into rectangles and wrap around the purple log to form the loaf

Step 12

Place the dough in the prepared loaf pan. Cover with tea towel and allow to double for a second time, about 1 hour.

Step 13

Preheat oven to 375ºF

Step 14

Remove the tea towel and bake the bread for 30 minutes, until slightly browning on top and an inserted toothpick comes out clean.

Step 15

Cool completely before slicing.