1sheetpuff pastry, partially thawedcut into 12 rectangles
½cupfreshly grated Parmesan cheese(50 g)
2tbspunsalted butter
1tspsalt
1tspDijon mustard
1.5cupschicken stock(355 ml)
1onionchopped finely
500gbutton mushrooms, sliced thick(1 lb)
⅓cupall-purpose flour(41 g)
1tspdried thyme
1eggbeaten
1tspsesame seedsoptional
Instructions
In a large skillet, heat the olive oil over medium-high heat. Add the chopped onion and minced garlic, cooking for 2-3 minutes until they become fragrant and soft.
Next, add the diced chicken along with salt and pepper. Cook for about 4-5 minutes, stirring frequently until the chicken is golden.
Incorporate the sliced mushrooms and continue cooking for another 4-5 minutes until they begin to soften.
Add the butter and allow it to melt, then stir in the flour.
Lower the heat to medium-low and gradually whisk in the chicken stock, milk, and thyme. Let this simmer uncovered on medium-low heat for 15 minutes, stirring occasionally (the sauce should bubble gently and will thicken).
Mix in the Dijon mustard and grated Parmesan cheese; allow it to cool slightly.
Preheat your oven to 425°F (220°C).
Transfer the filling into a pie dish (about 12 inches in diameter or 30 cm).
Lay the puff pastry rectangles over the filling, slightly overlapping them to cover completely.
Brush the pastry with the beaten egg and sprinkle with sesame seeds, if desired.
Bake for 30-35 minutes, or until the pastry is golden brown and crispy.