Create a rule that a Prime Minister can only be elected by a General Election

Background

I believe that the electorate should determine who is Prime Minister not the Members of Parliament. For example Boris Johnson was elected by the public but ousted by the Members of Parliament without any public consultation.

Additional details

The public feel disenfranchised with politics. We are asked to vote at general elections based on policies and individuals but the political parties then do not honour their manifestos. There is no accountability to manifesto pledges.