Hit the saute button on your pot, and add the beef and onion to the inner pot. Cook, breaking up & crumbling as it does until the beef's cooked through & completely browned.
Add the garlic, stirring to incorporate, and cook another 60 seconds. Hit the cancel button to stop the cooking process.
Scoop out and discard any obvious grease.
Add all of the remaining chili ingredients, except the tomato pasta, salt, & pepper. Stir everything together to evenly combine.
Add the lid, turning to close, and make sure the vent valve is set in the sealed position.
Cook on HIGH pressure for 20 minutes, then carefully turn the vent valve to perform a quick release. Carefully open the lid and avoid any escaping hot steam.
Add the tomato paste, and stir it in until evenly combined.
Hit the saute button again, and let the mixture simmer for 5-10 minutes- stirring often. When it's reached the thickness you prefer, hit the cancel button. Stir again to prevent it from sticking to the bottom as it sits.
Serve the warm chili over a plate or bowl of cooked spaghetti noodles, and garnish with shredded cheese and diced onion.