Spray a 9-inch springform pan with baking spray and set aside.
Grind the walnuts, transfer to a medium dish, mix in the honey or maple syrup for a vegan version and press the mixture tightly into the springform pan. Place in the fridge for 10 minutes to chill.
Place all the ingredients into a blender and blend until smooth, about 30 seconds. Pour mixture into the pan and bake until top and edges are slightly browned, about 50 minutes. The center will look set, but it will be just a little giggly.
Cool on the counter, transfer to the fridge and refrigerate until thoroughly chilled and firm, about 6 hours. Store in the fridge.