Heat a large skillet over medium-high heat with 1 tbsp. of oil (2 tbsp. for 4 servings). Set a large pot with salted water on to boil. Once boiling add pasta and set timer for 5 minutes.
In a large bowl empty the beef, spice blend, egg, breadcrumbs, and salt and pepper. Mix ingredients together well. For the best results use clean hands to incorporate everything. Form the mixture into 1.5 inch diameter meatballs. Place meatballs into the hot skillet for 5-6 minutes on each side and cook all the way through. Remove from skillet and set aside.
When the timer goes off for the pasta add the kale to the pot of pasta. Cook kale and pasta together for 1 minute, then drain altogether in sieve.
In the empty skillet, using the leftover oil from the meatballs, add the mushrooms and cook till they reduce in size by half and turn golden brown. Reduce heat to medium, then sprinkle in the flour, and add Worcestershire Sauce, mustard, crumble in the stock cube, 1.5 cups of water (3 cups for 4 servings), and 1.5 cups of milk (3 cups for 4 servings). Simmer the sauce until it thickens.
Add the meatballs back into the sauce and simmer all together for another 5 minutes. Taste the sauce and adjust seasoning as desired, adding salt and pepper if necessary.
To plate, divide the pasta and kale between serving plates, top with meatballs and sauce. Enjoy!