Make sure to check the puff pastry package for thawing instructions. The Dufour brand that I used requires 2-3 hours of thawing in the fridge.
Prepare your shredded chicken if you haven't already. Add chicken breasts to a large pot, season with salt and then cover with 1" of water. Bring to a boil over high heat. Once boiling, reduce heat to low, cover and let simmer for 10-20 minutes (based on size of chicken breasts), until the chicken is cooked through.
Transfer cooked chicken breasts to a large bowl or the bowl of your stand mixer. For the easiest and quickest shredding, use a hand or stand mixer. You can also just shred it with two forks. Set aside the shredded chicken.
Preheat oven to 425F.
Bring a 12" oven safe skillet (I like using cast iron) to medium heat. Once hot, add butter and oil. Let the butter melt.
Once the butter is melted, add diced onion & stir. Then, add salt, pepper and curry powder. Stir and continue cooking for about 3 minutes until the onion is starting to get tender.
Add the garlic and let it cook for 1 more minute until fragrant. Add the flour and stir so that the onion gets coated in it. Continue cooking for about 2 minutes until the flour smell has gone away.
Then, slowly add in the chicken broth, stirring after each addition. Slowly add in the coconut cream in the same fashion.
Once the mixture is bubbling, reduce heat to low and let simmer for 5 minutes or until thickened slightly.
Taste and adjust seasoning as needed. This would be a good time to add some cayenne if you want it spicier!
Then, add in the shredded chicken breast and frozen veggies. Stir until the chicken and veggies are coated in the curry sauce. Spread out in the pan so that it's flat and even. Remove the pan from heat.
Lightly flour your work surface. Roll out your puff pastry with a rolling pin just slightly so that the seams are smoothed out. Then, use a pizza cutter or sharp knife to cut the puff pastry into roughly 2.5" squares (20-25 squares total).
Then, place the puff pastry squares over the top of the skillet. There will be some overlap. If your pan is any smaller than 12", you will likely have excess puff pastry squares that you can discard or use for something else.
In a small bowl, whisk the egg. Then, use a pastry brush to apply the egg wash to the puff pastry - you won't use it all. Sprinkle generously with flaky salt (or normal salt if you don't have it) and black pepper.
Transfer the skillet to the oven and bake for about 40 minutes, or until the puff pastry is deeply golden in color.
Let cool for a few minutes before digging in. I like to serve it with some fresh chopped cilantro on top! Enjoy :)