Preheat oven to 190C/374 F

Slice the sweet potatoes, I used a mandolin to ensure the same size, they should be about 0.5 cm/1/4 inch wide

Prepare the sauce by combining plant based cream with nutritional yeast, rosemary, crushed garlic, salt and pepper in a large bowl.

Add the sliced sweet potatoes to the bowl and gently toss them until each slice is evenly coated. The goal is to have every slice bathed in this creamy, savory sauce, as it will infuse them with flavor as they bake.

Lightly grease a baking dish with olive oil or vegan butter. This prevents sticking and adds a bit of richness to the gratin. Layer the sweet potatoes in the dish, overlapping each slice slightly. Pour the remaining cream on top, until halfway. This will help create that bubbly, golden top we’re after.

Cover the dish with damp parchment paper, which helps keep the gratin moist while it bakes. Place it in the oven and bake for 20 minutes. After this, remove the parchment paper and bake uncovered for an additional 30 minutes. This second round of baking allows the top to brown and get bubbly. The sweet potatoes should be tender when pierced with a fork, and the sauce will have thickened and reduced to a luscious, creamy consistency.