To start, make the cashew cream. In a medium bowl, add cashews and cover them with boiling water. Let them soak for about 30 minutes. This softens the nuts, allowing them to blend into a smooth cream.
Once soaked, drain the cashews and transfer them to a high-speed blender. Add about half a cup of fresh water and blend until smooth. If the mixture is too thick, add a little more water until you reach a creamy consistency. Season with salt to taste.
Next, take a large skillet or a Dutch oven and place it over medium-high heat. Add the vegan butter and wait until it melts and begins to foam. This step is crucial as it adds a velvety richness to the dish.
Add the sliced mushrooms and minced garlic to the skillet. Sprinkle in salt and pepper, then cook for approximately 5 to 7 minutes. You'll notice the mushrooms will release their moisture, creating a savory base for the sauce.
Stir in the flour and cook for one more minute. This will help thicken the sauce. Then, whisk in the vegetable broth, scraping the bottom of the pan to incorporate all the delicious bits stuck to the skillet.
Bring the mixture to a boil while whisking constantly. This is an essential step that ensures everything is well combined and thickened nicely.
Once boiling, reduce the heat to medium and whisk in the cashew cream. Let it simmer for about 5 minutes, or until the sauce has thickened. Adjust seasoning with more salt and pepper if needed.
Meanwhile, cook the frozen green beans in the microwave according to package instructions. You can also microwave them on high for about 4 to 5 minutes, letting them stand for a minute before removing. Drain them well.
Once the green beans are prepped, add them to the skillet with the mushroom sauce. Gently toss until they are well coated with the sauce.
Transfer the mixture into a crockpot. Cook on high for 2 hours or low for 4 hours, until heated through. Before serving, top with fried onions for that perfect crunch!