Slice the onion into wedges and separate the shimeji mushrooms by hand.

Cut the bacon into 1cm wide strips.

Boil water in a pot, add salt, and cook spaghetti 1 minute less than the package instructions. Drain water.

Heat salad oil in a frying pan over medium heat, sauté bacon briefly, then add onion and shimeji mushrooms. Cook until softened.

Add water to the pan and bring to a boil. Turn off the heat, add cream stew roux, and stir until dissolved. Simmer on low heat for 5 minutes until thickened. Add milk and bring to a boil.

Add the cooked spaghetti to the sauce and mix well.