Steam the butternut squash until barely tender (10 minutes or so). Remove half of the squash pieces and set aside.
Steam the remaining squash until very tender (4 to 6 minutes). Mash this squash and set aside.
In a large saucepan set over medium-high heat, bring the chicken broth to a simmer.
Add chicken breasts, cover, and cook until chicken is cooked through (15 minutes).
Transfer the chicken breasts to a plate and allow to cool. Pour broth into a medium-sized bowl.
Return the saucepan to the stovetop and lower heat to medium. Add olive oil.
Add thr onion and cookuntil onion is starting to turn brown, (about 8 to 10 minutes)
Add the salt, minced garlic and oregano. Cook, stirring, for 1 additional minute.
Now, add tomatoes and all of the butternut squash. Stir to combine.
Stir in the chicken broth and quinoa. Bring to a simmer, cover and cook about 15 minutes.
Shred the chicken.
Stir in the chicken and pepper into the stew and simmer, uncovered, about 5 minutes.
Once heated throughout, serve.
