- Preheat oven to 375ºF. Cook macaroni in salted boiling water for 7 minutes, until al dente. Strain and set aside.
- While pasta cooks, melt butter over medium heat in a large oven-safe skillet. Whisk in flour to thicken. Gradually whisk in milk. Add 1 cup of cheddar cheese and 2 cups of white cheddar cheese. Stir until cheese is melted and sauce is smooth. Stir in Takumi sauce.
- Fold in macaroni until completely coated in cheese sauce. Sprinkle remaining cheese on top. Bake for 25-30 minutes, until cheese is bubbly and golden brown.
- Serve hot, topped with green onion, and drizzled with remaining Takumi sauce.