- Heat oven to 400 degrees F.
- Heat half of the olive oil over medium-high heat in a large oven-safe pan (I use a 10-12″ cast iron skillet, but a dutch oven or large flat-bottomed skillet work too)
SEAR THE CHICKEN:
- Season chicken thighs on all sides with salt and pepper.
- Gently add chicken thighs to the hot skillet and sear for 2-3 minutes per side until you have a nice, slightly brown crust. Don’t worry if they’re not fully cooked – they’ll finish cooking in the oven.
- Remove seared chicken thighs to a plate and set aside. Return the skillet to the stove.
MAKE THE SAUCE:
- Add the remaining olive oil to your skillet and turn the heat to medium.
- Add onion and garlic to skillet and sauté 2-3 minutes until onion has softened.
- Add diced potatoes to skillet and stir to combine. Cook another 2-3 minutes until potatoes have softened and developed some color.
- Add mushrooms to skillet and give everything a stir. Cook another 2-3 minutes until mushrooms have softened and reduced in size.
- Add the chopped fresh rosemary and another pinch of salt and pepper to taste. Stir to combine.
- Add chicken stock to pan a little bit at at time, stirring well between each addition to scrape off any browned bits from the bottom of the pan (that’s where the flavor is!)
- Add the heavy cream to the sauce and stir to combine.
BAKE IT ALL UP:
- Return the seared chicken to your skillet, nestling each piece into the sauce.
- Place the skillet in your hot oven and bake for 15-20 minutes until potatoes and chicken are each cooked through.
THICKEN & FINISH THE SAUCE:
- Remove skillet from oven.
- Spoon 2-3 tablespoons of sauce out of the skillet (careful, it’s hot!) and into a small bowl or measuring cup.
- Add cornstarch to bowl and whisk to combine. This is your cornstarch slurry.
- Slowly add cornstarch slurry back to skillet a bit at a time, stirring to combine. It can take a minute or two to thicken up – you may not even need the whole slurry, so just keep an eye on it!
- Add spinach and parmesan cheese to sauce and stir until cheese is melted. Garnish with an extra sprig of rosemary (optional) and serve immediately.
This looks like a lot of steps, but I promise it isn’t too complicated! I made the recipe instructions a little longer because I wanted you to be able to see the order of operations at a glance.
I used chicken thighs for this recipe because it’s what I usually have on hand, but you can use any cut of chicken you like! I’d recommend sticking with skinless because the skin can get rubbery when it sits in the sauce too long, but you could use bone-in thighs, chicken breasts, or anything else you have on hand!
Use a roux instead of a cornstarch slurry to thicken this sauce if you like. I recommend a roux of 2 Tbsp. butter and 2 Tbsp. flour just before you add the chicken stock.
Lighten this dish up by substituting milk or additional chicken stock for the heavy cream.
Use any veggies you like here! Broccoli, arugula, peppers, cauliflower, and roasted butternut squash are all great additions.
Use fresh thyme instead of rosemary if you like, or substitute 1/2 tsp. dried rosemary for the fresh leaves.
Shred your own parmesan cheese for this recipe – store-bought shredded cheese often has additives that prevent it from melting smoothly.
The exact consistency of your sauce can vary, and everyone has different preferences, so don’t worry if it doesn’t look perfect yet! Try one of these tricks to adapt the sauce to your liking: If you’d like a thicker sauce, make a bit more cornstarch slurry. If you’d like more sauce, you can increase the amount of chicken stock in the recipe. Less sauce? Decrease the amount of stock and cream. To thin the sauce out, add an extra splash of stock or milk.