Sauteing vegetables: Select the saute mode on the pressure cooker for medium heat. Add butter and stir until melted. Add diced onions, carrots, and celery, cooking for about 5 minutes until onions are soft, stirring frequently. Turn off the saute mode.
Pressure cooking: Add chopped broccoli and 2 cups of water, and stir. Secure the lid and seal the vent. Cook for 5 minutes at high pressure, immediately followed by a manual pressure release.
Stirring in dairy: Uncover and select the saute mode. Add heavy cream and garlic, and stir. Gradually add shredded cheddar cheese, stirring in until melted and well-mixed. Turn off the saute mode.