1. For the beef-style bouillon, I like Better Than Bouillon's No-Beef Base. It's what I use all the time in recipes calling for a beefy flavored broth.
2. If you don't have rigatoni on hand, any medium-size pasta, such as penne, ziti, mostaccioli, etc., will also work just fine.
3. Regarding the meatballs, be sure to use ones that are in their "raw meat" form. For this recipe, I used Beyond Meat Meatballs.
4. A single 8-ounce container of Trader Joe's vegan pesto is the perfect size for this recipe. However, if you've got basil to use up and feel inclined to make your own, my 5-Minute Vegan Basil Pesto is delicious!
5. Violife brand cheeses melt really well, making them my current favorite for baked dishes where you really want the cheese to get nice and... cheesy.