Heat 2 tablespoons of butter in a skillet over medium heat and add the onion and garlic. Sauté for about 2 minutes until fragrant.

Add the shredded chicken, chicken broth, salt, pepper, and parsley to the skillet, stirring constantly for about 3 minutes until the liquid reduces and the mixture becomes thick.

Transfer the filling to a bowl and let it cool completely.

Combine the milk, chicken broth, and 4 tablespoons of butter in a medium saucepan and bring to a simmer over medium heat.

Stir occasionally, ensuring the mixture doesn't boil over.

Add the minced onion to the simmering liquid and cook for 1 minute.

Gradually add the flour while stirring constantly with a wooden spoon until all the flour is incorporated and you have a smooth, thick paste.

Continue cooking the dough mixture over medium heat for about 5 to 7 minutes, stirring constantly until the dough pulls away from the sides of the pan.

Season with salt and pepper, then transfer the dough to a plate and let cool for about 15 minutes.

Once the dough is warm, wet your hands slightly with cold water and take about 2 tablespoons of dough.

Flatten it into a disk, place about 1 teaspoon of the cooled filling in the center, fold the edges up, and pinch to seal.

Coat each shaped coxinha in whisked eggs and then in panko breadcrumbs.

Heat oil in a deep pot to 350 degrees Fahrenheit.

Carefully lower the coxinhas into the hot oil and fry for about 2 to 3 minutes, turning until golden brown.

Transfer to a paper towel-lined plate to drain excess oil.

Let the fried coxinhas rest for a few minutes before serving.