Heat a large skillet over medium high heat. Add the ground beef and break up the meat. Half way through browning the ground beef, move to one side of the skillet. Add the onion, mushrooms and garlic to the empty side of the skillet.

Keeping the onion mixture separate from the beef, continue to stir until onion starts to soften. Once the onion has started to soften and the mushrooms have started to wilt, mix the beef with the onion mixture to fully combine.

Next add in the salt, pepper and fresh baby spinach to the skillet meat mixture. Carefully fold the fresh baby spinach into the beef mixture until leaves are fully wilted.

Turn off heat and stir in the lemon juice. Taste for seasoning and enjoy.