Place milk, broth and stock powder in a large saucepan. Bring to a very gentle simmer over medium heat, add chicken and thyme.

Place lid on, simmer gently on medium low for 15 minutes (do not boil, can make milk split).

Remove chicken, shred or dice (don't worry if inside a bit uncooked). Cover pot and set poaching liquid aside.

Melt butter in a large pot over medium high heat. Add garlic and onion, cook for 2 minutes. Add thyme, carrot and celery, cook for 3 minutes or until carrot is softened.

Add wine. Stir, scraping the bottom of the pot, and cook for 1 1/2 minutes or until wine is mostly evaporated.

Add flour and stir for 1 minute.

Add about half the reserved poaching liquid and stir until all flour is incorporated - it will be a thick sludge.

Add remaining milk broth, parmesan, pepper. Stir.

Add chicken and peas, stir.

Once mixture is heated (you'll see steam), cook for 3 minutes to thicken the sauce, stirring regularly. (Note 3)

Remove from heat. Spoon into oven proof pots - 4 large or 6 small (Note 4). Cool in fridge at least 30 minutes. (Note 5)

Meanwhile, remove puff pastry from freezer to partially thaw. Then use a bowl as a guide to cut rounds from the pastry about 2.5cm / 1" wider (all the way around) than the pots - be generous!

Preheat oven to 180C/350F.

Brush edge of pots with egg. Top with puff pastry, folding down the edges.

Brush pastry with egg. Cut a 2cm / 2/3" slide in the middle with a small knife.

Bake 35 - 40 minutes until deep golden.

Serve immediately!