Add the avocado, yogurt, mayo, garlic, arugula, herbs, chives, lemon juice, salt and pepper to a food processor and blend until combined. You want the mixture to be creamy and spreadable!
To make the melts, add the tuna to a large bowl. Add the baby arugula. Add about 1/4 cup green goddess dressing to start and toss the mixture together until everything is combined.
Spread a spoonful of the green goddess dressing on each piece of toast. Top with the tuna mixture. Top each with about 1/2 ounce of havarti cheese. Heat the broiler in the oven to high and place the tuna toasts under for just 1 to 2 minutes, until the cheese is melty. Serve immediately with potato chips or whatever side you'd like!