Cut bacon into 1 inch length. Separate shimeji mushrooms into individual stalks. Mince garlic cloves.
Wash spinach bunch and cut off the roots. Then, cut spinach into about 1.5 inch length. Separate leaf and stem parts (Don’t throw away the stems!)
Start cooking spaghetti according to the instruction on the package. Make sure to reserve one cup of the water you used to cook pasta.
In a large pan, cook garlic and red pepper flake with olive oil on a low heat.
Once garlic starts smelling delicious, add bacon and continue cooking on low heat.
Add stems of the spinach and shimeji mushroom. Once cooked, add spinach leaf and stir. Turn off the heat.
Add drained pasta into the pan. Add one cup of reserved pasta cooking water and soy sauce and mix well.
Salt and pepper to taste. Serve with parmesan cheese.