Leftover mashed potatoes work great here! Use approximately two cups mashed potatoes for the recipe.
Equipment
- Large pot
 - Medium saucepan
 - Whisk
 - 9" pie plate
 
Potatoes:
- 1.5 lbs Little Potatoes
 - 1/4 cup butter
 - 1/2 cup milk
 
Filling:
- 3 Tbsp butter
 - 1 onion, diced
 - 2 Tbsp all-purpose flour (or your favorite gluten-free blend)
 - 1 tsp dried oregano
 - 1/2 tsp dried thyme
 - 1/2 tsp paprika
 - (To taste) salt and pepper
 - 1 clove garlic, minced
 - 1 cup milk
 - 1/4 cup chicken broth
 - 1/4 cup heavy whipping cream
 - 1/2 Tbsp coarse whole grain mustard
 - 2 lbs cooked chicken breasts, cubed
 
Instructions
- 
                                        
Step 1
Place potatoes into a large pot of salted water. Bring to a boil and cook until tender, about 10 to 15 minutes. Drain and set aside.
 - 
                                        
Step 2
Return saucepan to the stove over medium heat. Melt butter and stir in milk. When bubbling, add potatoes and mash until desired consistency is reached.
 - 
                                        
Make the Filling:
Add butter to a medium-sized saucepan over medium heat. When bubbling, stir in onion. Cook for a few minutes.
 - 
                                        
Step 4
Whisk in flour and cook for about five minutes, or until roux is noticeably darker in colour.
 - 
                                        
Step 5
Stir in oregano, thyme, paprika, salt and pepper, and garlic. Whisk until combined.
 - 
                                        
Step 6
Add in milk, broth, cream, and mustard. Continue to whisk over medium-heat until thickened, about five minutes. Remove filling from heat.
 - 
                                        
Step 7
Grease a nine-inch round pie dish. Add mashed potatoes, pushing down and up the sides until you have a nice, even layer.
 - 
                                        
Step 8
Place into 400 °F preheated oven and bake for 10 minutes. Remove, add chicken, followed by sauce. Spread evenly and return to oven. Bake for 20 minutes, or until heated through.
 - 
                                        
Step 9
Allow to cool (a lot) before serving!