For the Mini Meatballs: In a medium bowl, combine ground beef, breadcrumbs, egg, grated Parmesan cheese, salt, and pepper. Mix until just combined, then roll into small, 1-inch meatballs. Set aside.

Cook Pasta: Bring a large pot of salted water to a boil. Add penne pasta and cook according to package directions until al dente. Drain and set aside, reserving about 1 cup of pasta water.

Brown Meatballs: While pasta cooks, heat olive oil in a large skillet or Dutch oven over medium-high heat. Add mini meatballs and brown on all sides until cooked through, about 5-7 minutes. Remove meatballs from the skillet and set aside, leaving any drippings in the pan.

Make Vodka Sauce: Reduce heat to medium. Add chopped onion to the skillet and sauté until softened, about 3-4 minutes. Add minced garlic and red pepper flakes (if using), and cook for 1 minute until fragrant.

Carefully pour in the vodka. Bring to a simmer and cook for 2-3 minutes, scraping up any browned bits from the bottom of the pan, until the alcohol has cooked off. (Careful, it might flame up briefly).

Stir in the crushed tomatoes and bring to a gentle simmer. Cook for 10-15 minutes, allowing the sauce to thicken slightly. Season with salt and pepper to taste.

Stir in the heavy cream and chopped fresh parsley. Return the cooked mini meatballs to the sauce and simmer for another 2-3 minutes to heat them through.

Add the cooked penne pasta to the sauce, tossing to coat. If the sauce is too thick, add a splash of reserved pasta water until it reaches your desired consistency. Serve immediately, garnished with extra Parmesan cheese and fresh parsley if desired.