Melt the butter using the Sauté function of the pressure cooker. When melted, add the butter. Stir in the garlic and onion and saute for 2-3 minutes, until the onion is soften and translucent.
Stir in the corn; let cook another 2 minutes.
Add in the potatoes, chicken broth, salt, pepper, and herbs, scraping any browned bits form the bottom of the pot.
Place the lid on the pot and lock into place. Set the pressure valve to sealing. Cook on HIGH pressure for 15 minutes.
Quick release the pressure and carefully remove the lid. Season with salt and pepper. Stir in the sour cream and cheese.
Blend the soup, using either an immersion blender in the pot or in a traditional blender, until smooth.