Set Instant Pot to sauté mode and add the oil, then add in the ground beef and brown for about 5 minutes making sure to break up the beef.
Stir in the onion and cook for 5 minutes, until softened.
Stir in the garlic, taco seasoning, salsa, tomato sauce and stock and mix, making sure to deglaze the insert well by scraping with a wooden spoon.
Then add the pasta, making sure it is fully submerged.
Cover and seal the Instant Pot, set to pressure cook / manual pressure on high for 4 minutes.
When done, perform a full quickly pressure release, open the lid, add in the peppers, half and half, and cheese.
Cover and let stand for 5 minutes, allowing peppers to soften and cheese to melt. Then open the lid, stir, and serve.