Peel and wash the rutabagas, and dice them into 1/2 inch cubes. Stovetop method: Place them in a large saucepan. Cover with water and bring to a boil. Let simmer uncovered for 35-40 minutes, or until the rutabagas are fork tender. Instant Pot method: Place the rutabaga in the Instant Pot liner and cover with water. Close the lid and pressure cook for 9 minutes. Let the pressure release naturally before opening the lid.
In the meantime, prepare the cashew cream. Drain the soaked cashews and add them to a blender. Add the cup of water and onion powder, and blend on high speed until smooth, about 1 minute. Set aside.
Once cooked, drain the rutabaga and transfer to a food processor. Process for 5-7 seconds or until it has the texture of mashed potatoes, don’t process too much as you want to have a slightly chunky texture.
Transfer the mashed rutabaga to a large mixing bowl. Add the blackstrap molasses, cashew cream, salt, and spices. Using a wooden spoon or spatula, mix to combine. Once fully combined, taste and adjust the saltiness to your liking.
Preheat oven to 325°F (160°C). Transfer the rutabaga mixture to a baking dish and smooth the top using a spatula. Sprinkle the breadcrumbs evenly on top. You can now use a spoon to make a pattern on top of the gratin, this is optional.
Bake for 1 hour, or until the top is golden brown. Let cool a few minutes before serving.
This rutabaga grating will make a delicious side dish on your holiday table! It can be served with brussel sprouts, green beans, vegan meatloaf, or even a vegan wellington!