Shred rotisserie chicken into bite-sized pieces, removing all skin and bones. Dice carrots, celery, and onions uniformly - this prevents some pieces being raw while others turn to mush. Keep frozen peas separate until the very end. Chop fresh herbs and set everything aside in organized bowls. This prep work is what separates successful chicken pot pie from disasters.

Heat olive oil in large skillet over medium heat. Sauté diced vegetables until softened but not mushy, about 6-8 minutes. Add butter and let melt completely. Sprinkle flour over vegetables and cook for exactly 2 minutes, stirring constantly - this eliminates raw flour taste. Gradually whisk in chicken broth, then cream, preventing lumps from forming. Add shredded chicken, herbs, salt, and pepper. Filling should coat spoon but not be paste-thick.

Preheat oven to 425°F. Roll bottom crust and fit into 9-inch deep pie dish with overhang. Here's the crucial step everyone skips: let filling cool for 10-15 minutes. Hot filling melts pastry and creates soggy bottoms. Pour cooled filling into crust, sprinkle frozen peas on top. Cover with top crust, seal edges by crimping with fork tines. Cut 4-5 steam vents. Brush with beaten egg for golden color.

Start at 425°F for first 15 minutes to set and crisp the crust. Reduce to 375°F and continue baking 35-40 minutes until crust is deep golden brown and filling bubbles actively through vents. If edges brown too quickly, tent with foil strips. Don't underbake - soggy crust ruins everything. The filling should be bubbling vigorously when done.

Remove from oven when beautifully golden and filling bubbles steadily. Let rest 10-15 minutes before cutting - this allows filling to thicken proper