Skillet chicken pot pie

Ingredients

• 1 (1/2 450-g pkg) frozen all-butter pre-rolled puff pastry , thawed overnight in refrigerator
• 3/4 cup plus 2 tsp milk
• 1 tbsp canola oil
• 1 onion , finely chopped
• 1/2 tsp dried thyme leaves
• 400 g skinless, boneless chicken thighs , cut into 1/2-inch pieces
• 3 tbsp all-purpose flour
• 1 1/2 cup vegetable broth
• 1/2 tsp salt
• 1 medium yellow potato , cut into 1/2-inch cubes
• 3/4 cup frozen peas
• 3/4 cup frozen corn kernels