Spray two rimmed baking sheets with an oil mister (or line them with parchment paper). Put the cauliflower on one sheet and the squash and pepper on the other. Coat the vegetables with an oil mister or toss them with a drizzle of olive oil and sprinkle with salt and pepper. Roast the vegetables for 20 minutes, stir, and roast for an additional 20 minutes or until the they're tender and just beginning to brown. Remove from the oven and cool slightly.
Put ½ cup of broth, squash and pepper pieces in a blender or food processor and process until smooth. If sauce is too thick, add the remaining broth. Season to taste with additional salt and pepper if desired.
In a large bowl, combine the sauce, cooked penne, and cauliflower; toss to coat and divide into bowls.
To make the Crispy Parmesan Circles, heat the oven to 425ºF and line a baking sheet with parchment paper. Divide the cheese into 4 large circles on the baking sheet — the individual cheese shreds should touch, but they shouldn't overlap too much or they won't get crispy. Bake for 10-15 minutes, until crispy and browned on the edges.