, cut into bite-sized pieces
Preheat oven to 400F. Unroll pastry (it will measure 10 x 10 in. square). Cut into 4 squares. Set on a lightly oiled baking sheet. Top each square with onion and pepper. Bake in centre of oven until pastry is lightly golden, 18 to 20 min.
Heat a large saucepan over medium-high. Add oil, then chicken. Cook, stirring often, until no pink remains, about 3 min. Remove to a bowl. Reduce heat to medium. Add butter. When melted, whisk in flour. Cook, whisking constantly for 1 min. Slowly whisk in milk until evenly mixed. Bring to a gentle boil, then stir in chicken, peas, broccoli and salt. Season with pepper. Cook until broccoli is tender-crisp, 3 to 5 more min. Remove from heat and stir in lemon juice. Spoon about 1 cup chicken mixture over each baked puff-pastry square.
Nutrition (per serving)
Substitution Tip: If you have turkey leftovers, use 2 cups, chopped, instead of chicken breasts.