Preheat the oven to 400˚F (200˚C, or gas mark 6).
In a roasting pan, combine the butternut squash, onion, yogurt, and curry powder.
Cook for 20 to 25 minutes, until the squash is tender when pierced with a knife.
Toss the roasted squash with the cooked millet.
Continue with the instructions for the frittata, pouring the egg mixture into the skillet and omitting the cheese in the base recipe.
Before placing the frittata in the oven, sprinkle the butternut squash mixture and shredded Havarti over the eggs.
