In a small bowl, combine the breadcrumbs and just enough of the milk to moisten them throughout. Pour a little bit in, mix, and repeat until they are all moist.
In a large bowl, combine the ground beef, egg, onion, garlic, thyme, rosemary, salt and pepper.
Mix together very well.
Add in the breadcrumb mixture and mix until combined.
Add more milk until the consistency of the meatballs is soft and slightly sticky. You should be able to roll them into balls and have them stay in shape easily.
Form into 1-inch balls, I like to use a 1-inch cookie scoop for this job.
Freeze in a single layer on a cookie sheet for 10 minutes, if time allows. This makes them hold up better for frying.
In a large heavy bottomed pot, heat oil on medium high heat until shimmering.
Place meatballs in the dutch oven and fry until brown on all sides. Don't crowd the dutch oven, you'll need to do about three batches. Remove fried meatballs from pan and store on a paper towel lined plate while you fry the rest.
The meatballs aren't fully cooked at this stage, you will finish cooking them in the sauce.
For the Sauce
Using the pot you fried the meatballs in, adjust fat to be about 2 tablespoons. You may have to remove some fat or add a tablespoon or so of butter.
Add 2 tablespoons of flour and cook on medium low for about 2-3 minutes.
Gradually pour in the beef broth, whisking the whole time. Let simmer until slightly thickened, about 3 minutes.
Add sour cream, cream, tomato paste, brown mustard, Worcestershire sauce, and all spice.
Taste and adjust seasonings with salt and pepper.
Add all of the meatballs into the sauce and gently make sure they are all covered and evenly distributed.
Bake in the oven, lid on, on the middle rack on 350 degrees F for 30-45 minutes.
Stir gently once finished, sprinkle with fresh parsley for serving, if desired.