Did the universe begin as matter or energy

The Big Bang theory is the prevailing cosmological description of the development of the Universe. Under this theory, space and time emerged together 13.799±0.021 billion years ago and the energy and matter initially present have become less dense as the Universe expanded.

Energy

Explanation:

"Soon after the Big Bang, primordial protons and neutrons formed from the quark-gluon plasma of the early Universe as it cooled below two trillion degrees. A few minutes later, in a process known as Big Bang nucleosynthesis, nuclei formed from the primordial protons and neutrons."

-wikipedia