Preheat the oven to 425°F. Cut the squash in half and scoop out the seeds, then cut into 1/4 inch slices. In a medium bowl, toss the squash slices with 2 tablespoons olive oil, several pinches kosher salt, and fresh ground pepper. Line a baking sheet with parchment paper and top with the squash slices. Roast until tender, about 30 to 40 minutes.
Meanwhile, in a medium saucepan, add the farro and 6 cups water. Bring to a boil, then simmer for about 15 minutes, until tender. When finished, drain and mix with a drizzle of olive oil and a pinch of kosher salt. (If you have an Instant Pot, go to Instant Pot Farro and use 2 cups farro and 3 cups water.)
Crush or chop the walnuts. In a small skillet, toast the nuts over medium to low heat, stirring occasionally, until they are brown and fragrant, taking care that they don’t burn.
In a small bowl, whisk together 4 tablespoons olive oil, the white wine vinegar, stone ground mustard, honey, and fresh squeezed orange juice. Season with a pinch of kosher salt and fresh ground pepper. Taste, and adjust seasonings if needed.
To serve, pile greens on a plate or in a bowl. Top with roasted squash, warm farro, toasted walnuts, and feta cheese crumbles. Drizzle with dressing and garnish with orange zest and fresh ground pepper.