Select Saute on your electric pressure cooker. Melt butter then add diced onion and sauté until it’s translucent.
Add minced garlic and cook until fragrant.
Stir in the chicken stock, broccoli, carrots, sea salt and black pepper.
Cook on High Pressure for 1-2 minutes. When the cook time is up, use a quick pressure release, then open the lid.
Whisk the cornstarch and cold water together in a small bowl.
Turn your Instant Pot onto Saute (high if possible) and slowly add the cornstarch slurry, stirring constantly, until the soup comes boils then thickens.
Stir in the heavy cream or half-and-half.
Add the cheese about ½ cup to the soup, and stir until the cheese melts. Taste and adjust salt and pepper, if needed.