Quick Recipe Version (TL;DR)
Quick Ingredients
- 3 tbsp (42 g) unsalted butter
- 1 tbsp (15 ml) olive oil
- 1 large yellow onion, diced (about 1 1/2 cups / 225 g)
- 2 medium carrots, diced (about 1 cup / 140 g)
- 2 celery stalks, diced (about 3/4 cup / 90 g)
- 3 cloves garlic, minced
- 1/3 cup (40 g) all-purpose flour
- 2 1/2 cups (600 ml) low-sodium chicken stock
- 1 cup (240 ml) whole milk
- 1/2 cup (120 ml) heavy cream
- 1 tbsp (15 g) Dijon mustard
- 1 tsp dried thyme (or 1 tbsp chopped fresh)
- 1 bay leaf
- 1 1/2 tsp kosher salt, plus more to taste
- 1/2 tsp black pepper
- 4 cups cooked chicken, shredded or diced (about 600 g)
- 1 cup (140 g) frozen peas
- 2 tbsp chopped fresh parsley
- 2 sheets puff pastry, thawed (about 17 oz / 480 g total)
- 1 large egg + 1 tbsp (15 ml) water (egg wash)
Do This
- 1. Heat oven to 400°F (200°C). Butter a 9×13-inch (23×33 cm) baking dish.
- 2. Sauté onion, carrots, and celery in butter + oil until softened, 8–10 minutes; add garlic for 30 seconds.
- 3. Stir in flour for 1 minute, then whisk in stock, milk, and cream; add Dijon, thyme, bay, salt, pepper; simmer until thick, 6–8 minutes.
- 4. Stir in chicken, peas, and parsley; remove bay leaf; pour filling into dish.
- 5. Lay puff pastry over the top, trim, and crimp to the edges; cut 6–8 steam vents; brush with egg wash.
- 6. Bake 25–30 minutes until deep golden and bubbling; rest 15 minutes; cut into squares.
Why You’ll Love This Recipe
- Perfect for a crowd: baked in one big pan and sliced into neat buffet squares.
- Classic comfort: creamy chicken-and-vegetable filling with a crisp, flaky puff-pastry lid.
- Approachable and flexible: use rotisserie chicken, leftover roast chicken, or cooked turkey.
- Make-ahead friendly: prep the filling in advance, then top and bake when you’re ready.
Grocery List
- Produce: yellow onion, carrots, celery, garlic, fresh parsley (optional), fresh thyme (optional)
- Dairy: unsalted butter, whole milk, heavy cream, 1 egg
- Meat: cooked chicken (rotisserie or leftover)
- Frozen: frozen peas, puff pastry sheets
- Pantry: olive oil, all-purpose flour, chicken stock, Dijon mustard, bay leaf, kosher salt, black pepper
Full Ingredients
For the creamy chicken-and-vegetable filling
- 3 tbsp (42 g) unsalted butter
- 1 tbsp (15 ml) olive oil
- 1 large yellow onion, diced (about 1 1/2 cups / 225 g)
- 2 medium carrots, peeled and diced (about 1 cup / 140 g)
- 2 celery stalks, diced (about 3/4 cup / 90 g)
- 3 cloves garlic, minced
- 1/3 cup (40 g) all-purpose flour
- 2 1/2 cups (600 ml) low-sodium chicken stock
- 1 cup (240 ml) whole milk
- 1/2 cup (120 ml) heavy cream
- 1 tbsp (15 g) Dijon mustard
- 1 tsp dried thyme (or 1 tbsp finely chopped fresh thyme)
- 1 bay leaf
- 1 1/2 tsp kosher salt, plus more to taste
- 1/2 tsp freshly ground black pepper
- 4 cups cooked chicken, shredded or diced (about 600 g)
- 1 cup (140 g) frozen peas (no need to thaw)
- 2 tbsp chopped fresh parsley
For the puff-pastry lid
- 2 sheets puff pastry, thawed according to package directions (about 17 oz / 480 g total)
- 1 large egg
- 1 tbsp (15 ml) water
Equipment
- 9×13-inch (23×33 cm) baking dish (at least 2.5–3 inches / 6–7.5 cm deep)
- Large skillet or wide pot
- Whisk
- Pastry brush (helpful but optional)
Step-by-Step Instructions
Step 1: Preheat the oven and prep the pan
Arrange a rack in the middle of the oven and preheat to 400°F (200°C).
Lightly butter a 9×13-inch (23×33 cm) baking dish. Set it on a sheet pan if you want extra insurance against any bubbling over (optional, but tidy).
Step 2: Sauté the aromatics and vegetables
In a large skillet or wide pot over medium heat, melt the 3 tbsp (42 g) butter with the 1 tbsp (15 ml) olive oil.
Add the diced onion, carrots, and celery. Cook, stirring occasionally, until the onion is translucent and the vegetables have softened slightly, 8–10 minutes.
Add the garlic and cook just until fragrant, about 30 seconds.
Step 3: Build the roux (the thickener)
Sprinkle the 1/3 cup (40 g) flour over the vegetables. Stir constantly for 1 minute, coating everything well and cooking out the raw flour taste. The mixture will look a bit pasty and dry at first.
Step 4: Whisk in liquids and simmer into a creamy sauce
Slowly whisk in the 2 1/2 cups (600 ml) chicken stock a splash at a time, smoothing out any lumps as you go. Once it’s smooth, whisk in the 1 cup (240 ml) milk and 1/2 cup (120 ml) heavy cream.
Stir in the 1 tbsp Dijon mustard, thyme, bay leaf, 1 1/2 tsp kosher salt, and 1/2 tsp black pepper.
Bring to a gentle simmer over medium to medium-high heat, then reduce to medium-low and simmer, stirring often, until the sauce is thick and creamy, 6–8 minutes. It should coat the back of a spoon.
Step 5: Add chicken and peas, then fill the tray
Turn off the heat. Remove and discard the bay leaf.
Stir in the cooked chicken, frozen peas, and fresh parsley. Taste and adjust seasoning if needed (different stocks and chicken can vary in salt).
Spoon the filling into the prepared baking dish and spread into an even layer.
Step 6: Top with puff pastry and vent
Unfold the thawed puff pastry. If you have two sheets, overlap them slightly as needed to cover the dish (a small overlap is fine). Lay the pastry over the filling.
Trim excess pastry so it overhangs by about 1/2 inch (1 cm). Tuck the edge just inside the rim of the dish and press lightly to seal. If your dish has a rim, you can crimp gently with a fork for a tidy edge.
Cut 6–8 small slits in the pastry to vent steam (this helps keep the pastry crisp and prevents blowouts).
In a small bowl, whisk together 1 egg and 1 tbsp (15 ml) water. Brush a thin, even layer over the pastry.
Step 7: Bake until golden, then rest and slice
Bake at 400°F (200°C) until the pastry is puffed and a deep golden brown and the filling is bubbling at the edges, 25–30 minutes.
Remove from the oven and let the pot pie rest for 15 minutes. This gives the filling time to set up so you can cut cleaner squares.
Slice into 12 squares and serve warm.
Pro Tips
- Thick filling = tidy squares: simmer the sauce until it’s nicely thick before adding the chicken. A too-thin filling will ooze when sliced.
- Keep puff pastry cold: if your kitchen is warm, pop the topped (unbaked) dish in the fridge for 10 minutes before baking for a higher rise and flakier layers.
- Vent well: those small slits are key. Steam needs an exit so the pastry stays crisp instead of soggy.
- Don’t over-brown the edges: if the pastry edges color too quickly, loosely tent just the edges with foil for the last 8–10 minutes of baking.
- Best chicken options: rotisserie chicken is fast; leftover roast chicken is especially flavorful. Aim for bite-size pieces so every square has plenty of chicken.
Variations
- Turkey tray-bake pot pie: swap the chicken for the same amount of cooked turkey (great for leftovers).
- Extra-veg version: add 1 cup (120 g) sliced mushrooms (cook them with the onion) and/or 1 cup (150 g) frozen corn (stir in with the peas).
- Herby lemon twist: add 1 tsp lemon zest and increase parsley to 1/4 cup for a brighter, fresher finish.
Storage & Make-Ahead
Refrigerate: Cool completely, cover, and refrigerate for up to 4 days. Reheat individual squares on a sheet pan at 350°F (175°C) for 12–15 minutes (this re-crisps the pastry better than the microwave).
Freeze: You can freeze baked squares, tightly wrapped, for up to 2 months. Thaw overnight in the fridge and reheat at 350°F (175°C) for 15–20 minutes.
Make ahead: Make the filling up to 2 days ahead and refrigerate. When ready to bake, warm the filling on the stovetop until just loosened (so it spreads easily), transfer to the dish, top with pastry, and bake at 400°F (200°C) for 25–30 minutes.
Nutrition (per serving)
Approximate per 1 of 12 servings: Calories: 430; Protein: 23 g; Carbohydrates: 29 g; Fat: 25 g; Fiber: 3 g; Sugars: 5 g; Sodium: 760 mg.
