Select the Sauté setting on the Instant Pot and after a few minutes, add the olive oil. Once the oil has heated up, add the leeks. Cook until starting to soften, 3-4 minutes. Add garlic and cook for 1 minute.

Add the cauliflower florets, thyme sprigs, 3/4 teaspoon of the kosher salt, and black pepper to taste. Pour the vegetable broth on top and stir.

Secure the lid and set the valve to Sealing (not Venting). Select the Pressure Cook setting (or Manual setting on older models) at high pressure and set the cook time to 4 minutes.

Once the 4-minute timer has completed and beeps, perform a quick pressure release by switching the valve from Sealing to Venting.

While the cauliflower is pressure cooking, make the miso butter. Combine the 2 tablespoons of miso paste with the 2 tablespoons of vegan butter in a small saucepan over low heat. Gently heat together and stir for 1-2 minutes until the ingredients are combined together.

Open the Instant Pot and add in the miso butter, nutritional yeast, and remaining ½ teaspoon kosher salt. Using an immersion blender, blend all of the ingredients together until you have a smooth texture. Alternatively, transfer all of the ingredients to a food processor and blend until smooth. Taste for salt and adjust accordingly.