Preheat the oven to 400 degrees F. Grease a medium casserole dish with a little butter and set aside.
In a large pot, add the oil and allow it to get nice and hot over medium heat. Add the yellow onion, bell pepper, garlic and jalapeno and season lightly with a touch of salt and pepper. Allow the veggies to cook until they have developed some color and cooked down a bit, 4 to 5 minutes.
Add the butter and stir it in until melted. Add the flour and stir everything together. Stir for about a minute to cook out any raw flour taste.
Add the chicken stock, sazon seasoning, chili powder, granulated onion, granulated garlic, paprika, oregano, green chiles and hominy. Bring to a boil, reduce the heat to medium and allow to simmer for about 10 minutes.
Add the cooked chicken along with the pearl onions and cream. Allow everything to simmer together for another 10 minutes. Season with some salt and pepper and stir in the cilantro.
On a lightly floured surface, roll out the puff pastry so it¿s about an inch bigger on all sides than your casserole dish.
Pour the chicken mixture into the prepared casserole dish, then lay the puff pastry on top, tucking in the sides. Make a few slits in the top of the pastry with a paring knife. Brush the pastry with some egg wash and sprinkle a little salt and pepper all over the top. Bake the pot pie until the top is a lovely golden brown color, 20 to 25 minutes. Allow to sit for about 10 minutes before serving.
There are a lot of ingredients here, but you probably have many of them in your pantry. Feel free to leave out what you don't have and mix it up with what you do. For example, the hominy can be swapped with diced potatoes (just add them with the chicken stock so they have a chance to cook). And the pearl onions can be skipped if you don¿t have them, or you can substitute chopped scallions or chives.