Add the cashews to a blender and blend into a powder. Do not blend too much or the oils from the cashews will start to release and form a type of wet sandy texture.
Place a fine mesh strainer over a bowl and dump the cashew powder into the strainer. Shake and scrape the sides of the strainer to strain all of the fine cashew powder into the bowl. Add any large cashew pieces that won’t go through the strainer back to the blender and pulse into a powder. Return the contents of the blender to the strainer and shake again to release the cashew powder into the bowl. Repeat this process until all cashews are blended into a fine powder.
In a medium saucepan, add the water and sugar and stir to dissolve. Bring the mixture to a boil and keep boiling, whisking often, for approximately 4 minutes.
Remove the pan from the heat. Add the cashew powder and stir to combine. The mixture will quickly start to thicken.
Add the coconut oil, and any flavor additives if preferred and stir to combine.
The cashew fudge is done when the dough mixture resembles a firm cookie dough. It should not be dry and crumbly at all and it also shouldn’t be too wet and sticky. You should be able to scoop it with a spoon and have it hold its shape without breaking into crumbly pieces. If the dough is crumbly, add more coconut oil, 1 teaspoon at a time, and mix until combined and the dough is the right texture. If the dough is too sticky and doesn’t hold its shape, add the pan back to the stovetop over low heat and cook, stirring often, for about 1 - 2 minutes until the dough is slightly thickened.
Generously grease a cutting board with coconut oil and place the dough on it. Place a piece of parchment paper over the dough and use a rolling pin to roll it out until it is 1⁄4 inch in thickness.
Allow the cashew fudge to cool slightly, but not completely, before cutting it angled into diamond shapes. I recommend using a large knife for easier cutting. Store the cooled fudge in an airtight container in the fridge for up to 1 week.