Prep the meatballs first. Mix together all the ingredients for the meatballs then cover for about 15 minutes. After, roll the meatballs by hand.
In a pan on medium high heat, add about 2-3 tablespoons of oil then sear the meatballs on 1-2 sides. Just sear them unitil they are golden. They will finish cooking through later. Remove them once they are golden, then sit to the side.
Once the meatballs are removed, add in the garlic and onion. Add a little more oil if needed but you don't want the pan dry. Cook the onion and garlic until browning then add in the butter. Once the butter has melted, sprinkle in the flour and cook the flour with the onions and garlic for 1 minute.
Next, whisk in the chicken broth first. Then, pour in the milk. Sprinkle in the garlic powder and nutmeg and continue whisking until it starts to thicken.
Once thicken, lower the heat to low then add back in the meatballs. Allow the meatballs to cook in the sauce while it simmers. This should take 10 minutes more or less. Once the meatballs are done, remove the them once again.
Add in the heavy cream and spinach. Now, continue to stir as it thickens and spinach withers down. You may need to add the spinach in batches, it'll all fit once withered.
Lastly, season the sauce with salt and pepper to taste. Serve the meatballs and spinach together with the sauce. Garnish with a helping of parmesan cheese.