Place an oven rack in the center of the oven and preheat to 400 degrees F. Spray a heavy nonstick baking sheet with vegetable oil cooking spray.
For the filling: Heat the oil over medium-high heat in a 12-inch skillet. Cook the onions, salt and pepper, stirring frequently, until soft, about 6 minutes. Add the turkey and cumin. Cook until the turkey is cooked through, about 5 minutes. Add the spinach and cook until wilted, about 2 minutes. Remove the skillet from the heat and add the beans. Mash the beans until smooth, using a fork. Stir in the mascarpone.
Place a nonstick skillet over medium-high heat. Brush each side of the tortillas with olive oil. Cook the tortillas in batches until warm, about 30 seconds. Spoon about 1/4 cup of the filling into each tortilla and roll up into a cigar shape. Place the tortillas, seam-side-down, on the baking sheet and sprinkle with Cheddar. Bake until the Cheddar is melted and the tortillas are crisp and golden, 25 to 30 minutes. Cool for 5 minutes and serve with salsa and guacamole.