In a large mixing bowl, combine the panko breadcrumbs and milk, letting sit for 2 minutes to form a panade. Add the ground beef, grated parmesan, egg, minced garlic, parsley, Italian herbs, sea salt, black pepper, and nutmeg.

Gently mix the ingredients together with clean hands just until combined—avoid over-kneading to keep the meatballs tender. Roll into 16 to 18 golf ball-sized meatballs (about 1.5 inches each).

Heat 2 tablespoons of olive oil and 1 tablespoon of butter in a large deep cast iron skillet over medium-high heat. Add the meatballs in a single layer and sear for 5 to 7 minutes, turning occasionally until browned on all sides. Transfer seared meatballs to a plate (they will finish cooking in the sauce).

In the same skillet with accumulated beef drippings, melt the remaining 1 tablespoon of butter over medium heat. Add the dry orzo pasta and sliced garlic. Toast for 2 minutes, stirring constantly until the orzo turns fragrant and lightly golden.

Pour in the beef bone broth, stirring to scrape up any caramelized fond from the bottom of the skillet. Bring to a gentle boil.

Nestle the seared meatballs back into the skillet among the orzo. Reduce the heat to medium-low, cover with a lid, and simmer for 9 to 11 minutes until the orzo is al dente and the meatballs are cooked through (internal temp 165°F / 74°C).

Remove the lid and reduce heat to low. Stir in the heavy cream, 1/2 cup of grated parmesan cheese, and fresh lemon juice, gently tossing with the orzo until a velvety sauce forms.

Add the baby spinach and fold through for 1 to 2 minutes until wilted and vibrant green.

Remove from heat. Garnish with chopped fresh parsley, extra cracked black pepper, and serve hot directly from the skillet with lemon wedges.