Place chicken stock and dried mushrooms (if using) in a microwave-safe container and microwave on high power until simmering, about 5 minutes. Transfer porcini to a cutting board and roughly chop. Add fresh mushroom scraps to container with porcini-infused stock and set aside to infuse.

Heat olive oil and butter in pressure cooker over high heat, swirling, until foaming subsides. Add fresh mushrooms, season with salt and pepper, and cook, stirring occasionally, until excess moisture has evaporated and mushrooms are well browned, about 8 minutes.

Add onion, garlic, and chopped porcini (if using) and cook, stirring frequently, until onions are softened, about 4 minutes. Add rice and cook, stirring, until rice is evenly coated in oil and toasted but not browned, 3 to 4 minutes. Stir in soy sauce and miso paste until evenly incorporated.

Add wine and cook, stirring, until raw alcohol smell has cooked off and wine has almost fully evaporated, about 2 minutes.

Pour stock into pot through a fine-mesh strainer, discarding mushroom stems. Close pressure cooker and bring up to low pressure (10 psi on most units). Cook at low pressure for 5 minutes, then depressurize cooker, either by running it under cold water if it is not electric or using the steam-release valve if it is electric.

Open pressure cooker and stir to combine rice and cooking liquid; a creamy consistency should begin to develop. Stir in cream (if using), cheese, and herbs. If risotto is too soupy, cook for a few minutes longer, stirring, until it begins to thicken more. If it is too thick, stir in some hot water. It should flow slowly when you drag a trail through it with a spoon. Season to taste with salt and pepper and serve immediately on hot plates, passing extra cheese at the table.