Place the sugar and coconut oil in a mixing bowl and mix on high speed until combined,
Add the gluten free flour, cocoa powder, baking soda, and salt to the bowl, Add the vinegar and water and then beat on medium speed until smooth.
Pour batter into cake pan and bake at 350 degrees F for about 35-40 minutes, or until a toothpick inserted in the middle of the cake comes out clean.
Cool in pan for 45 minutes, then loosen the edges with a knife and invert onto a cake plate. Don’t remove from the pan too soon, because it might fall apart – gluten free flour is a little bit more delicate.
Make the Frosting:
Melt the buttery spread in a heavy bottomed saucepan over medium heat.
Add the sugar, and stir frequently. It will melt and start to thicken a bit.
Combine the cornstarch and non-dairy milk in a small container with a lid. Shake well and drizzle the mixture into the pan a little bit at a time, stirring constantly. The frosting should start to thicken.
Stir in the coconut and pecans (if you are using), and heat through. If the frosting seems too sugary and thick, you may have to add a little bit more non-dairy milk. As it cools, it will thicken up.
Spoon the frosting over the cake. You could also slice the cake first and spoon sauce on top of each slice individually. This is the best way to do it if you want nice, neat slices.
Notes
Store leftover cake in an airtight container. It should stay fresh for up to 4 days.You can make the sauce without nuts if you wish. Just add more coconut flakes.If you aren't gluten free, go ahead and use regular all-purpose flour.