Preheat the oven to 450 degrees F.
In a large bowl, toss the peppers, zucchini, squash, and onions with the olive oil, vinegar, Cascade Mushroom Mix, El Greco, 1/2 teaspoon salt, and 1/2 teaspoon pepper. Transfer to a baking sheet and roast until just fork tender, about 15 minutes.
Reduce the oven temperature to 350 degrees.
While the vegetables are roasting, bring a large pot of salted water to a boil, add the pasta, and cook for about 6 minutes. Drain in a colander. Note that, because you are cooking it a second time, you will want the pasta to be still firm inside.
In a large bowl, toss the drained pasta with the kale, roasted vegetables, marinara sauce, 1 cup feta, and the remaining salt and pepper. Gently mix until all the pasta is coated and the ingredients are combined.
Pour the pasta mixture into a greased 9"x13" pan. Top with the remaining feta, and bake until the top is golden and the cheese begins to melt, about 25 minutes.