The Concise Encyclopedia of Economics, Sheldon Richman succinctly states: “As an economic system, fascism is socialism with a capitalist veneer.”7 He contends that socialism seeks to abolish capitalism outright, while fascism gives the appearance of a market-based economy, even though it relies heavily on the central planning of all economic activities. According to authors Roland Sarti and Rosario Romeo, “[U]nder Fascism the state had more latitude for control of the economy than any other nation at the time except for the Soviet Union.”8
https://www.econlib.org/library/Columns/y2015/Samuelsfascism.html
Mussolini founded fascism in 1919 as an alternative left-wing revolutionary movement to socialism.
A rising star of the Italian Socialist party and a brilliant editor of its newspaper Avanti!, he had been expelled from the party in 1914 because he opposed its policy that Italy should remain neutral in the first world war. Instead, the future Duce believed that Italy must go to war against Austria and Germany which it eventually did in 1915. He insisted that socialists could not wait for history, as Marxist doctrine preached. They must make history, he argued, and such a war would help, not hinder, the revolution.
https://www.spectator.co.uk/article/how-mussolini-invented-fascism/