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4.75 from 8 votes

Low Carb Tuna Casserole (With Cauliflower)

Prep Time10 minutes
Cook Time30 minutes
Total Time40 minutes
Servings: 4 -6
Author: Lexi


  • 2 tablespoons butter
  • 1 onion diced
  • 2 celery stalks diced
  • 3 cloves garlic
  • 3 tablespoon arrowroot
  • 2-1/2 cups cashew milk or milk of choice
  • 1 tablespoon dijon mustard
  • 1 teaspoon ground black pepper
  • 1 teaspoon fine sea salt
  • 1/2 teaspoon paprika
  • pinch cayenne optional
  • 1/2 cauliflower about 1 lb., cut into florets (For Low Carb Version use 1 whole cauliflower, about 2-2-1/2 pounds and slice into pieces about 1/4" thick)
  • 2-4 oz cans genova tuna drained
  • 6 ounces brown rice pasta cooked al dente (For Low Carb Version Omit This)
  • 1/3 cup frozen green peas optional
  • 3/4 cup shredded sharp cheddar cheese divided
  • scallion for garnish


  • Pre-heat oven to 400ºF.
  • Heat a large heavy bottom pan, over medium heat and melt butter. Add onion and celery cook until beginning to soften, about 5-7 minutes.
  • Add garlic, and cook for 30 seconds.
  • Sprinkle in arrowroot, and then slowly whisk in cashew milk (or milk of choice) a 1/2 cup at a time to avoid any lumps. (see note)
  • Add dijon mustard, salt, pepper, paprika and cayenne, if using, and whisk to combine.
  • Add cauliflower and simmer for 5 minutes, stirring occasionally.
  • Remove from heat and stir in 1/2 cup of cheese. Then add in Genova Seafood Tuna, al dente cooked pasta (Omit for Low Carb Version), frozen peas and mix to fully combine.
  • Pour into an oven safe dish (if not using one already) and top with remaining 1/4 cup cheese and bake until cauliflower is tender and cheese is melted, 15-20 minutes. If you want the cheese to be bubbly and slightly browned, place under the broiler for 3-5 minutes.
  • Top with scallions and let sit for 5 minutes before serving.


The sauce may seem really thick before it goes in to the oven, but the cauliflower and the tuna exude a lot of liquid so the extra thick sauce stops it from becoming to0 watery after it is baked.


Calories: 208kcal | Carbohydrates: 9.7g | Protein: 20g | Fat: 10.1g | Saturated Fat: 5.6g | Cholesterol: 42mg | Sodium: 551mg | Fiber: 2.3g | Sugar: 4.5g