Ingredients

2 large yellow onions, halved and thinly sliced (about 5–6 cups sliced)

2 tbsp unsalted butter

1 tbsp olive oil

1 tsp kosher salt, divided (½ at the start, ½ later)

¼ tsp black pepper

1 tsp sugar (optional, helps promote browning)

1–2 tbsp dry white wine (optional flavor booster)

½ tsp balsamic vinegar (optional flavor booster)

½ tsp Worcestershire sauce (optional flavor booster plus 1 tbsp for casserole)

1 ½ cups uncooked orzo

2 cups shredded cooked chicken (rotisserie or leftover roasted)

2 cups beef broth

1 cup chicken broth

½ cup heavy cream (or half-and-half for lighter)

2 cloves garlic, minced

1 tsp dried thyme or 1½ tsp fresh thyme leaves

½ tsp onion powder

Additional salt & pepper, to taste

1 ½ cups shredded Gruyère cheese

½ cup shredded mozzarella

¼ cup finely grated parmesan (optional for browning and sharpness)

Optional garnishes: fresh thyme sprigs, parsley, crispy fried onions, a drizzle of cream or dollop of sour cream, fresh cracked black pepper

Instructions

Step 1: Heat the butter and olive oil in a large oven-safe skillet over medium heat until the butter melts and begins to foam.

Step 2: Add all the sliced onions and sprinkle with ½ tsp salt. Stir occasionally as onions soften and become translucent, about 5–8 minutes.

Step 3: Reduce heat to medium-low, add sugar if using, and continue stirring every few minutes as the onions caramelize and darken, about 20–35 minutes total. Adjust heat to avoid burning.

Step 4: Optional: Deglaze the pan by adding white wine, balsamic vinegar, or Worcestershire sauce. Cook 1–2 minutes until liquid mostly evaporates.

Step 5: Add the remaining ½ tsp salt, black pepper, and minced garlic. Cook 1 minute until fragrant. The onions should be soft, jammy, and golden brown.

Step 6: Add uncooked orzo directly to the onions. Stir to coat in butter and onion mixture. Toast for 1–2 minutes until fragrant and nutty.

Step 7: Pour in beef broth and chicken broth, stirring to loosen any bits stuck to the pan.

Step 8: Stir in heavy cream, then fold in shredded chicken evenly.

Step 9: Add Worcestershire sauce, thyme, onion powder, and black pepper. Taste and adjust salt if needed.

Step 10: Increase heat to medium-high and bring mixture to a gentle simmer. Avoid a rolling boil. Once simmering around edges, remove from heat.

Step 11: Cover skillet with lid or tightly with foil and bake in a preheated 400°F (205°C) oven for 18–22 minutes, until orzo is tender and most liquid is absorbed.

Step 12: If casserole looks watery, bake uncovered for an additional 3–5 minutes. Remove from oven and sprinkle Gruyère, mozzarella, and parmesan if using on top. Bake a few more minutes to melt and brown cheese if desired.

Step 13: Garnish with fresh thyme, parsley, crispy fried onions, and a drizzle of cream or sour cream if you like. Serve warm.

Tips & Variations

For a lighter dish, substitute half-and-half for heavy cream or use all chicken broth instead of beef broth.

Caramelize onions slowly to develop the deepest flavor; patience is key for the best taste.

Use leftover rotisserie chicken to save time without sacrificing flavor.

Add mushrooms or a handful of spinach before baking for extra veggies.

Try substituting orzo with other small pasta shapes like acini di pepe or couscous if you prefer.

FAQs

Can I make this casserole ahead of time?

Yes, you can prepare the casserole up to the baking step, cover it, and refrigerate. Bake it straight from the fridge, adding a few extra minutes to the baking time.