I have a pile of twigs and leaves, too. The soil is great to plant trees or bushes in. Amazingly dark because of the high carbon content. Perfect soil for funghi. Leaf
compost lacks nitrogen, potassium and other stuff so it is quite poor soil even though it looks great and crumbly. Certainly too poor for most veggies. I would fertilize it with liquid gold, molasses, rockdust and of course kitchen scraps whilst building your keyhole garden. Rockdust is lightly alcaline and neutralizes the acidic tannines from oak leaves.