Tuna Alfredo (with Jarred or Homemade Sauce)

Fill large pot with 16 cups water. Place pot on stovetop over high heat and bring water to rolling boil.
Once water begins to boil, add 1 tablespoon salt to pot and stir to incorporate. Allow water to return to rolling boil.
When water is once again boiling, add 1 pound fettuccine to pot. Boil pasta until al dente, 1 to 2 minutes less than time indicated on pasta packaging.
When pasta is al dente, pour pasta into colander, reserving pasta water to use in sauce if needed. Drain pasta well and set aside.

Place large skillet on stovetop over low heat. Add 1 16-ounce jar alfredo sauce to skillet and heat sauce until warm, stirring occasionally.
When sauce is warm, add 1 teaspoon Italian seasoning and 1 large pinch crushed red pepper flakes to skillet and stir to incorporate. Simmer sauce 1 minute, stirring occasionally.

Place large skillet on stovetop over low heat. Add ½ cup unsalted butter and 1 ½ cups heavy whipping cream to skillet. Simmer ingredients 2 minutes, whisking constantly until fully incorporated and warmed through.
When mixture is warm, add 2 teaspoons minced garlic, 1 teaspoon Italian seasoning, and 1 large pinch crushed red pepper flakes to skillet. Whisk to incorporate, then simmer mixture 1 minute, whisking occasionally.
Remove skillet from heat. Add 1 tablespoon finely chopped fresh parsley and 2 cups grated parmesan cheese to skillet and whisk until cheese is melted and fully incorporated into sauce. Return skillet to heat.

Add drained fettuccine to skillet of alfredo sauce. Toss pasta in sauce until fully coated, adding small amounts of reserved pasta water if needed to achieve desired consistency.
After coating pasta in sauce, add 2 5-ounce cans chunk light tuna in water to skillet. Gently fold flaked tuna into pasta until well distributed.
Portion tuna alfredo onto serving plates. Garnish pasta with finely chopped fresh parsley if desired and serve immediately with torn pieces of baguette (optional).