Tear up the bread, put it in a small bowl, pour over the oat milk and leave to soak for 10 minutes.
Transfer the bread mix to a food processor, add the walnuts, oil, garlic, nutritional yeast, salt, pepper, and lemon zest and juice, then blend to a mostly smooth sauce studded with a few small, crunchy, nutty bits for good measure.
Cook the pasta in boiling, well-salted water (I used two teaspoons of salt for two litres of water) according to the packet instructions, or until al dente
Just before the pasta has finished cooking, scoop out a mug of the starchy cooking water and put to one side. Drain the pasta well.
Put the pasta back in the empty pan on a low heat, then add the walnut and bread sauce and 100ml (about seven tablespoons) of the reserved cooking water. Toss for a few minutes, until the sauce turns creamy and coats the pasta.
Stir in the oregano, then distribute between plates or shallow bowls, and serve topped with a drizzle more olive oil, if you wish.
