Preheat oven to 375 F. Line a roasting pan with foil.
Place the cut squash, carrots and parsnip in a medium bowl or zip bag.
Season veggies with olive oil, garlic, dry mustard, salt, and black and red pepper. Pour onto prepared pan and distribute evenly. Begin roasting root veggies in the oven as you prep the salmon.
Place the salmon on a foil-lined baking sheet. Sprinkle with the everything bagel seasoning. Put the salmon into the oven and roast for 12 minutes.
After the vegetables have roasted for 15 minutes, remove them from the oven. They should be slightly soft and a little caramelized.
Meanwhile, divide the spinach leaves among 4 plates.
Make the dressing by combining all remaining ingredients in a small measuring cup and whisking.
When the salmon comes out of the oven, top the spinach with the slightly cooled vegetables, and drizzle with dressing.
Place a salmon fillet alongside the spinach. Enjoy!