Step 1

In a large pot, cook pasta in boiling salted water for 5-6 min. or about 5min. away from al dente according to the package. Add the broccoli and cook for the last 5 min. Drain well and return to saucepan.

Step 2

Preheat oven to 400F. Grease a 9x13" casserole dish and set aside.

Step 3

In a medium saucepan, melt the butter over low heat and then add the flour, stirring. Add salt and pepper to taste and cook for 1 min. Whisk in milk and increase heat to medium high. Continuue whisking until mixture starts to boil and thicken. The sauce will be fairly loose still. Remove from heat and stir in 1/2 cup each of Swiss and cheddar cheese. Stir to melt.

Step 4

Add the cheese sauce to the pasta and broccoli along with the tuna. Pour into the prepared dish. Arrange tomato slices on top and cover with remaining cheese.

Step 5

Cover with foil and bake for 20 min. of until hot and bubbly.