Select "Sauté" mode and adjust to more. When hot, add oil and butter. Add onion to the pot; cook and stir for 2-3 minutes. Add the minced garlic, paprika, mustard, and cayenne pepper to the pot. Cook for another 45 seconds to 1 minute stirring constantly until fragrant. Add in the flour and whisk to combine. Cook for 2-3 minutes, whisking constantly until the flour is thickened (it will look like a thick paste). Press “Cancel”.
Add broth, bay leaf, broccoli, and carrots; mix to combine.
Close lid and Select "Pressure Cook" mode adjust to 5 minutes. When cooking is complete press “Cancel” and carefully turn the vent to “Venting” to release the pressure. Then remove the lid.
Blend (optional): At this point, you can blend some of the soup or use an immersion blender, if desired. For chunky texture: use an immersion blender, stand blender, to puree the soup until you reach the desired texture. For smooth and silky texture: Let the soup cool down a little. Transfer the soup to a blender and blend until smooth. Return to the instant pot. NOTE: I like to remove (with a slotted spoon) about 2 cups of broccoli before blending it, next I blend the soup until smooth and then return the saved broccoli to the blended soup.
Select "Sauté" mode and adjust to less. Stir in cheese mixture. Cook and stir for 2-3 minutes until the cheese is melted. Taste for seasoning and adjust with more salt and pepper if necessary. Add heavy cream; mix to combine. Let the soup simmer for 2 minutes.
Serve immediately with bread rolls or biscuits.