- 4 Tbsp butter
- 2 cloves garlic, minced
- 1 small white onion, diced
- 4 Tbsp flour*
- 2 cups milk (any fat %), warmed to not quite boiling
- 1 tsp dried thyme
- 1 tsp dried oregano
- 1 cup grated cheddar cheese
- 1 cup grated Gruyere
- salt and freshly-ground black pepper
- 1.5 lbs. potatoes (I used Russet) very thinly sliced
- 1 lb boneless, skinless chicken breasts, cubed
- 1 1/2 cups fresh green beans, cut to 1″ segments
- 1 lemon, halved and thinly sliced
- Preheat the oven to 425 F.
- In a large saucepan over medium heat, melt the butter. Add the garlic and onion, and cook until softened — 3-5 minutes.
- Whisking constantly, add the flour. Continue to whisk and cook the roux for 3 minutes before adding the hot milk, thyme, and oregano. Whisk and cook until the mixture comes to a boil and thickens. Cook for another two minutes, then add the cheese, whisk until fully melted, and remove from heat. Add salt and pepper to taste.
- In a large bowl, combine the potatoes, chicken cubes, green beans, and cheese sauce. Mix well to fully coat everything in the sauce, then pour into a large casserole pan (I used a 9×13 baking dish, but could have gone bigger!).
- Tuck the lemon sliced in along the top, cover with foil, and bake for 50-60 minutes, or until your potatoes are tender. Remove the foil, and broil until the top of the casserole is golden.
- Remove from the oven, and serve warm.
If you are making this gluten-free, be sure to use a gluten-free thickener in place of the flour. I’ve found Bob’s Red Mill All-Purpose GF Flour to work perfectly as a thickener when making a roux.