An emphasis on direct experience can be found throughout Buddhism, usually in the context of emphasizing its utility, while downplaying the usefulness of intellectual elaborations on Buddhist ideas. I.e., it's much better to have a single, concrete, personal experience of emptiness/non-self in meditation, than to read several volumes of Buddhist logic.
If you want to trot out the doctrinal stuff, Dharmadhātu probably what you're looking for - it's the label given to purified mind in its natural state, free of obscurations. It is the essence-quality or nature of mind,