Slow Cooker Chicken Cordon Bleu

This was SO DELICIOUS! First of all, the chicken cordon bleu is so great by itself, but add the sauce ... O.M.G. good! This might be one of my new favorite sauces. I can't put my finger quite on what was in the sauce that was so delicious, but you have to try it to believe it. Maybe you can figure it out?

Ingredients for the Chicken
4-6 boneless, skinless chicken breasts
4-6 slices swiss, provolone, or mozzarella
4-6 thin slices smoke ham
1/4-1/2 cup all-purpose flour to shake the chicken in

Ingredients for the Sauce
1 cup milk
1 cup whipping cream
1 cup chicken broth
1 1/2 cups cheddar, swiss, mozzarella, or colby cheese, grated
1/2 cup grated parmesan cheese
2 tablespoons butter
2 heaping tablespoons flour
1/2 teaspoon onion powder or sauteed onions
1/2 teaspoon pepper
1 teaspoon salt
1/4 teaspoon red pepper flakes, optional
2 teaspoons granulated sugar

Directions for the Chicken
1. Place a piece of chicken between two pieces of plastic wrap. Using a rolling pin or meat mallet, pound each chicken breast to 1/4 inch thickness. Continue this with the remaining chicken.
2. Season each piece of chicken with salt and pepper. Place 1 slice of cheese and 1 slice of ham on each piece of chicken.
3. Roll up each breast (tucking loose ends in if necessary) and using a toothpick to secure the chicken together.
4. Dredge each chicken roll in flour and shake of any excess.
5. In a skillet, add a few tablespoons of olive oil/butter and turn up your heat to medium high. When oil/butter is hot, carefully place your chicken rolls in the skillet and brown both sides of the chicken until nice and golden. Place browned chicken in the bottom of the slow cooker.

Directions for the Sauce
1. Over medium heat, melt butter and add the salt, pepper, pepper flakes, onion powder, and sugar. Whisk together. Add the flour and stir quickly until the roux is bubbly and smooth.
2. Add the broth, cream, and milk and continue whisking over medium heat until it has thickened, about 10 minutes.
3. Turn heat to low and add the grated cheeses. Stir well until nice and smooth (it should not be as thick as pancake batter, so if you want it thinner, add a little more water). If you want to add additional seasoning (I did), add it now.
4. Pour the sauce over the browned chicken in the slow cooker and cover with the lid. Cook on low for 5-6 hours or until chicken is fork tender.