Cook the Bacon: Set your Instant Pot to Sauté mode. Once the pot is hot, add the diced bacon and cook until it becomes crisp. Once done, transfer the cooked bacon to a plate and set it aside. Remove all but ¼ cup of the bacon grease from the Instant Pot.

Sauté the Vegetables: In the reserved bacon grease, add the diced onion and sauté for about 5 minutes, or until the onion becomes translucent. Stir in the minced garlic and cook for another 1-2 minutes until fragrant.

Add the Potatoes and Stock: Add the diced Yukon Gold potatoes and chicken stock to the Instant Pot. Stir to combine. Secure the lid on the Instant Pot with the vent in the Sealing position. Set to Manual High Pressure for 8 minutes.

Prepare the Cornstarch Slurry: While the potatoes cook, whisk together ¼ cup heavy cream and 3 tablespoons cornstarch in a small bowl until smooth.

Release Pressure and Mash: After the 8-minute cook time, carefully perform a Quick Release of the pressure and remove the lid. Set the Instant Pot back to Sauté mode. Use a potato masher to mash the potatoes to your desired consistency.

Thicken the Soup: Stir in the cornstarch slurry, the remaining heavy cream, salt, and pepper. Stir frequently and let the soup simmer for about 5 minutes until it thickens.

Add Cheese and Sour Cream: Once the soup has thickened, stir in the shredded cheddar cheese, sour cream, and the reserved crisp bacon. Continue stirring until the cheese melts and the soup becomes creamy.

Serve: Ladle the potato soup into bowls and serve warm with optional toppings such as crumbled bacon, shredded cheese, and sliced green onions.