Preheat oven to 375°F.
Melt butter in a large oven-safe skillet over medium heat.
Add onion, carrots, celery, garlic, chicken bouillon, thyme and cracked black pepper. Sauté until softened, fragrant and translucent without deeply browning.
Sprinkle flour over the vegetables and stir for 1–1 1/2 minutes.
Slowly pour in chicken broth while whisking. Continue whisking until smooth and beginning to thicken.
Add half-and-half and lightly squeeze in about half a lemon. Whisk together.
Bring to a boil, immediately reduce to a low simmer and cook for about 5 minutes, stirring occasionally.
Taste and season with onion powder, garlic powder, additional pepper and salt as needed.
Turn off the heat. Fold in shredded rotisserie chicken, frozen corn and frozen peas.
Arrange frozen biscuits over the filling, beginning around the perimeter and filling in the center.
Whisk egg yolk with about 1/4 cup half-and-half. Brush over the biscuit tops and sprinkle with dried parsley.
Bake at 375°F until the filling is bubbling and the biscuits are deeply golden and completely cooked through, using the package baking time as a starting point and adding additional time as needed.
Allow the skillet to rest before serving so the creamy filling can settle and thicken slightly.
