Preheat oven to 400 degrees F. Toss the sweet potatoes with the olive oil, spices (cinnamon, cumin, chili powder, salt, pepper, cayenne, if using), until well coated. Place in a single layer on a baking sheet and roast for 25-30 minutes, stirring halfway until potatoes are tender.
While the sweet potatoes are cooking, make the quinoa. Rinse the quinoa (I use a fine-mesh strainer) and place in a medium saucepan with 2 cups of water. Bring to a boil, then cover and reduce heat to low. Simmer for 12 minutes, then turn off heat and let sit for another 5 minutes. Fluff with a fork and let cool.
Whisk together the syrup, vinegar, dijon mustard, garlic, and salt until combined, then slowly drizzle in the olive oil, whisking the entire time until a dressing comes together. Taste, adding more salt/pepper as desired.
In a large bowl, combine the greens, cooked potatoes, cranberries, goat cheese and cooked quinoa. Add the dressing and toss until well coated, then serve immediately.
