Preheat oven to 350 F. 

In a skillet, heat the oil for a minute or two, then add diced onion, and jalapeño (if using). Add chicken and one can of chilis. Add 1/2 cup of the chicken broth and cream then stir to combine. Let mixture begin to bubble and get hot, then remove from heat and set aside.

In a saucepan, add butter over medium heat and allow to melt. Whisk in flour and keep whisking to remove any clumps. Allow to cook for a minute or two, then slowly whisk in remaining chicken broth. Whisk and cook for another minute or two, then add remaining can of chilis. Reduce heat to low, then add sour cream. Add 1 1/2 cups of cheese and stir to let it melt and incorporate well. Add salt and pepper to taste.

Spread about 1/2 cup of the sauce mixture into the bottom of a greased 9x13 pan. To assemble, grab a tortilla, spoon chicken mixture on top, then add a sprinkling of cheese. Roll up, then place into the pan. Continue process with remaining tortillas. Top with remaining sauce mixture, then remaining cheese, if desired. Bake for 30 minutes. Topped with chopped cilantro, if desired.