Preheat the oven to 350 degrees F.
Wrap the tortillas in foil and heat in the oven for 10 minutes until softened. Remove from oven and set aside.
PREPARE THE SAUCE
Melt the butter in a large saucepan on medium-high heat. Add the onion, garlic, coriander, cumin and pepper and cook until onion is tender, about 5 minutes.
Stir the flour into the sour cream and add to the onion mixture.
Stir in the broth and cook and stir until thickened and bubbly.
Remove from the heat and stir in 1 1/2 cups of the cheese.
At this point, taste and add salt as needed.
Place the cooked chicken in a large bowl. Add 1 cup of the sauce, the spinach and 1/2 cup of the cheese and mix well.
Place about 1/4 cup of the filling on top of each tortilla and roll up.
Arrange the rolls, seam side down, on a lightly greased baking dish.
Top with remaining sauce and cheese and bake, covered with aluminum foil for about 35 minutes or until heated through and cheese is melted.
Remove from the oven and let stand for 10 minutes before serving.