Bring a large pot of water to a boil. Trim away the green part of the leeks as well as the root ends. Slice the leeks in half lengthwise, then cut into half moons. Drop the leeks into the boiling water and boil for about 30 seconds. Remove with a slotted spoon to a paper towel lined plate. Dry as much as possible with paper towels. Set aside.

Preheat the oven to 400ºF.

Place the sweet potatoes in a large bowl and drizzle with about 1/2 tablespoon olive oil. Spread on a baking sheet and place in the oven. Bake for 5 minutes. Meanwhile, place the cauliflower in the same bowl and drizzle with another 1/2 tablespoon oil. After the sweet potatoes have been roasting for 5 minutes, add the cauliflower and return to the oven for another 5 minutes. Combine the mushrooms and bell pepper in the bowl and drizzle with 1/2 tablespoon of oil. Add to the baking sheet and cook another 5 minutes. Combine the zucchini and blanched leeks in the bowl, drizzle with the last 1/2 tablespoon of oil and add to the baking sheet, stirring to combine. Bake another 5 minutes, or until all of the vegetables are roasted and tender.

Lay your tortillas out, and spread 1/2 oz of the shredded cheese on half of each of the tortillas. Top with about 1/2 cup of the roasted veggie mixture, then another 1/2 oz of cheese. Fold the tortilla in half.

Heat a large skillet over medium heat and spray with nonstick cooking spray. Working in batches, place 2 (or more if they fit in your skillet) of the filled tortillas in the skillet. Cook until both sides are browned and the cheese is melted.

Let cool for a minute or two before cutting into wedges and serving.