Step 1

Preheat oven to 375 degrees and place rack in center position

Step 2

Start water to boil and cook pasta to package instructions

Step 3

While water heats, grate cheddar and slice onions

Step 4

Place milk in a small pot on medium heat to warm

Step 5

In skillet melt butter on med/high. If not using a skillet melt in a medium sized pot

Step 6

When butter is melted add a 1/4 cup green onions and sauté for 2 minutes

Step 7

Add flour and whisk until smooth about one minute. This is a roux. A roux thickens your cheese sauce

Step 8

Slowly pour warm milk into roux with one hand while whisking with the other

Step 9

Add 4 cups cheese one handful at a time whisking between additions (reserving one cup of cheese for later)

Step 10

Whisk until all cheese is melted and sauce is smooth

Step 11

Season with salt and pepper

Step 12

When pasta is ready (do not overcook!) add to skillet with cheese sauce and stir until well incorporated. (If baking in a baking dish, pour pasta into baking dish and then pour cheese sauce over)

Step 13

Top with remaining cheese and bake for 20-25 minutes or until cheese is crispy

Step 14

Garnish with remaining green onions, serve