In a blender, puree the roasted beet pieces with the milk (start with 1/4 cup and add more as needed to puree it until smooth).
In a mixer, with a dough hook attachment, add the warm water and yeast. Mix until blended. Add the sugar and mix about a minute. Slowly mix in 1 cup of the flour until combined. Mix in the eggs one at a time until they are combined. Add in the pureed beets.
Add another 2 cups of the flour, oil, and salt. Mix together on medium-low speed stopping the machine to scrape down the sides of the bowl. Slowly add the rest of the flour (the remaining 4 cups) and mix until combined.
Stop the machine as you add each cup of the flour to scrape the sides of the bowl and incorporate the flour. Mix on low speed for 12 minutes until dough is incorporated. Be sure to give your mixer a break and as you don’t want to burn it out. Add flour if needed 1 tablespoon at a time. The dough will be a little sticky but also firm.
Take dough out of mixer bowl.
Form the dough into a ball and place into an oiled bowl (when I put the dough in the bowl I swish the dough around the bottom of the bowl and then flip it over so all of the dough is covered in a light film of oil). Cover with plastic wrap and let it rise at room temperature until doubled in size (about 1-1 1/2 hours).
Punch down the dough. Divide the dough into 6 equal portions. Shape each portion into a ball, and allow it to rest with plastic wrap on it for 5-10 minutes. You could divide the dough into 9 portions to make 3 smaller loaves.
Roll each dough ball into long piece .Braid 3 strands together to form a loaf. Repeat with the other 3 strands. Cover and let rise in a draft free place for about 45 minutes to 1 hour.
Preheat oven to 350 F.
When ready to bake, brush with egg wash. Sprinkle with poppy seeds or sesame seeds.
Bake the challah for 35-40 minutes. The bread should be golden brown. Ovens may vary so check your challah at about 30 minutes and see how it’s doing. You test if it’s done by tapping the bottom of the loaf. If it sounds hollow, it needs a bit more time.* Be careful to not burn your fingers like I did when you do that test. Let it cool and serve slightly warm or at room temperature.