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Butter or grease a 13x9 inch pan or another casserole dish large enough.
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Bring a large pot of water to a boil.
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Add the pasta and cook to the al dente state according to the directions on the package.
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While the pasta is cooking, preheat the oven to 350°.
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Again, while the pasta is cooking, heat a medium skillet to medium-high heat and add the butter. When the butter has melted, add the chopped onion and sauté until the onion begins to brown along the edges and has softened.
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Set aside to cool.
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When the pasta has finished cooking, drain and set aside to cool briefly while you prepare the casserole.
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In a large bowl, add the mayonnaise, yogurt, tuna, sesame oil, salt, and pepper. Stir well to combine. There should still be small chunks of tuna.
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Fold in the toasted onions, the Jarlsberg cheese, chopped almonds, and the sliced olives.
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Finally, mix in the pasta until thoroughly combined.
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Spread the mixture evenly into the prepared casserole dish.
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Sprinkle the panko crumbs evenly over the top, followed by the parmesan cheese.
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Bake for 35-45 minutes until the casserole is bubbling and the topping is golden brown.