To make the meatballs, combine the ground beef, breadcrumbs, milk, cream, parsley, mustard, salt, black pepper, red pepper flakes and eggs in a large mixing bowl. Mix together well with your hands. Scoop out 1-tablespoon portions and roll them into balls with your hands. Place the meatballs onto parchment-lined baking sheets and put the baking sheets in the freezer for 5 to 10 minutes for the meatballs to firm up.
To brown the meatballs, heat the olive oil in a heavy pot or large skillet over medium-high heat. Add the meatballs in batches, making sure not to overcrowd the pot. Cook, turning the meatballs to make sure they brown all over, 5 to 7 minutes per batch. Drain on paper towels.
Freezer instructions: Put the cooked meatballs in a single layer on baking sheets and put into the freezer. When frozen, divide them into freezer bags, 25 per bag, and return them to the freezer.
