Preheat oven to 400 degrees F. Line a small baking sheet with foil and spray lightly with nonstick cooking spray.
Place the butternut squash cubes, rosemary, 1/8 tsp. of the salt, 1/2 tsp. of the olive oil, 1 tsp. of the maple syrup and 1 Tbsp. of the brown sugar in a small bowl and mix until everything is combined and covered with oil/maple syrup, then spread the mixture out evenly in a single layer on the prepared baking sheet.
Bake in the preheated oven with the rack at the top for 8 minutes, then stir/flip the squash pieces over and continue cooking for ~10 minutes more, until tender (a fork goes through the chunks with no effort). While it's baking, you can make the quinoa.
Place the rinsed quinoa in a large-bottomed saucepan (I use my dutch oven) over medium to medium-high heat and sautee, stirring frequently, for ~5 minutes until toasted (be careful not to burn it).
Note: The package says to toast with olive oil, however I've noticed doing this leaves a bitter taste at the end, and according to the internet this is true and quinoa should be toasted on its own, without any oil. So I recommend not using oil for the toasting process.
Stir in the water, the remaining salt (1/4 tsp.) and the remaining brown sugar (1 Tbsp.) and heat until boiling.
As soon as the mixture starts boiling, cover the pan, reduce heat to low and simmer covered for ~15 minutes, until you see a visible small white spiral in each grain (this is the germ, which is visible once it has spiraled out), water has fully evaporated and quinoa is tender but not overcooked (when overcooked, quinoa is mushy).
When the quinoa is done, remove from the heat. Use a fork to fluff up the quinoa, then set aside.
Heat the remaining 1/2 tsp. of olive oil with the remaining 1 tsp. maple syrup in a small skillet over medium heat. When heated, add the sage and pine nuts and cook, stirring frequently (almost constantly) for ~2-3 minutes, until the pine nuts have browned slightly. Then, add in the spinach and cook, stirring constantly, until the spinach has wilted (should only take a minute).
Note: It's important to stir very frequently throughout this entire step to prevent the nuts and sage from burning.
Place the sage/spinach/pine nut mixture and the roasted butternut squash (both should be done now) into the saucepan with the quinoa/spinach mixture and mix everything together. Taste test and add additional salt if needed/desired.
Serve as a side dish or eat as a snack or mini-meal by itself. Store leftovers in an airtight container in the refrigerator for up to 4 days.