Prepare and Brown the Meatballs:
In a bowl, soak the croutons (or torn bread) in the milk.
Add the remaining meatball ingredients (parmesan, eggs, sea salt, garlic powder, and black pepper) and mix thoroughly to form the meatball mixture.
Shape the mixture into meatballs.
Brown the meatballs in a skillet, then remove and set them aside.
Fry the Onions:
In the cast iron skillet, add oil and heat over medium-high heat.
Fry the onions on both sides for three to five minutes until a desirable color has formed.
Season the onions with a sprinkle of salt and remove them from the pan.
Make the Gravy:
If the pan is dry, add butter.
Stir in the flour.
Whisk in the mushroom or vegetable stock.
Simmer and Finish:
Return the browned meatballs and minced garlic to the skillet with the gravy.
Simmer until the meatballs are cooked through and the gravy has thickened.Finish with salt and pepper to taste.
Top the dish with the fried onions before serving.