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.
Recipe courtesy of Ree Drummond