Peel and dice the sweet potatoes into 1 inch/ 2.5 cm cubes. Add to a medium-sized pan, cover with water and add 1/2 tsp salt. Boil oh high heat for 15 minutes until the potatoes are soft. Alternatively, you can cook the sweet potatoes in the microwave for 5 minutes in a bowl with a little water.
Set aside the potatoes to cool slightly. Meanwhile, peel and roughly chop the garlic then saute in a small frying pan with 1/2 tsp sunflower oil until fragrant.
OAdd the cooled sweet potatoes, sauteed garlic, soy milk, lemon juice, nutritional yeast, black pepper and remaining 1/4 tsp salt to a blender. Begin by blending on low speed then gradually increase the speed to high, until the sauce is creamy and smooth.
Meanwhile, boil the macaroni pasta in a large pot of salted water according to packet instructions. Drain the pasta and add back to the pot along with the blended sauce. Simmer on low heat until the sauce is bubbling. Serve hot and enjoy!
Optional additional step: Transfer the vegan mac and cheese to an oven-proof dish, top with your favourite dairy-free cheese (I like violife here in the UK), and bake for 15-20 minutes at 180 °C/ 350 °F until golden and bubbling.