What is the Biblical basis for the idea of 'creation ex nihilo'?

Dr. Dan McClellan in a recent video says > "[T]he doctrine of creation ex nihilo is not found anywhere in the > Bible. The academic consensus is that it is a creation of 2nd century > Christianity that arose within debates between Christians and Gnostics > and other Greco-Roman thinkers. In addition, Genesis 1:1 is not best > translated as "In the beginning, God created the heavens and the > earth," but as a temporal clause: "When God began to create the > heavens and the earth," and then verse 2 describes the circumstances > that obtained at that time." Well, is he right? What is the Biblical basis for the doctrine of 'creation ex nihilo' (creation out of nothing)?