In a large Dutch oven, cook pasta over medium-high heat as directed on the package. Set a timer for 1 minute less than the lowest time recommendation on the package. When al dente, drain the pasta and return to the Dutch oven.

Meanwhile, in a large skillet, brown lean ground beef with onions and garlic. Avoid stirring too much to allow the meat to brown. Pour beef into large pot with cooked noodles.

In the same skillet, place mushroom slices in a single layer and allow them to brown. Adding a little olive oil if needed. After both sides are browned, add the to the pot with cooked beef and cooked pasta. Leaving the cooking oils from mushrooms and beef in the skillet.

In the skillet with the cooking fats, add the flour and stir to make a paste. Add a little oil to make 2 Tablespoons, if needed. Cook over medium heat for 2-3 minutes until smooth and slightly browned.