Cut up one large potato into large chunks and add to Instant Pot with beer, chicken base, and spices. Cook on max pressure for 8 minutes or high pressure for 9, until the potatoes are fully cooked. Quick release when finished. While potatoes are cooking, make a roux base with 2 tablespoons butter and ¼ cup flour, cooking for a minute on medium to remove floury taste. When the Instant Pot quick release is finished, add roux base to beer and potatoes, and immersion blend to puree. Add stock cubes, remaining 2 cups of diced potatoes, and onions to the Instant Pot. Cook on max pressure for 1 minute or high pressure for 2 minutes and quick release. Potatoes should be tender at this point. Add cheese and whipping cream and mix until melted