Fill a large pot with water, place over high heat and bring to a boil.
Add a handful of salt and the pasta and stir. Bring back up to a boil and occasionally stir.
Cook pasta until al dente, about 6 to 8 minutes. Remove from heat and drain, reserving about 3 cups pasta water. Set aside.
Pour 1 ½ tablespoons oil into the pot and place back over medium-high heat.
Add shallot and garlic and sauté for 2 to 3 minutes.
Add cauliflower and continue to sauté for 2 to 3 minutes. Season with salt and pepper.
Stir in mustard and turmeric and continue to sauté for 2 to 3 minutes.
Pour reserved pasta water into the pot and simmer until cauliflower becomes fork tender, 6 to 8 minutes.
Using a slotted spoon, scoop cauliflower, shallots and garlic out of the pot and into the well of a blender.
Add nutritional yeast and 1 ½ cups of the reserved pasta water.
Blend on high, adding more water as needed.
With the motor running, add remaining 1 ½ tablespoons oil and season with salt and pepper.
Blend until a smooth, glossy and creamy sauce forms.
Pour mixture back into the pot and place over medium low heat.
Fold reserved pasta into the ‘cheese’ sauce until completely combined and evenly coated.
Adjust seasonings and serve.