Artichoke Leek Frittata

Name: Artichoke Leek Frittata
Ingredients: 2 tablespoons butter; 2 cups cleaned leeks , white and light green parts only, sliced (sliced in half lengthwise, then sliced crosswise, about 1/4-inch-thick slices) (see How to Clean Leeks ); 4 ounces frozen artichoke hearts , thawed, sliced into 1/2-inch slices; 1/2 teaspoon dried tarragon (can sub 2 teaspoons of chopped fresh tarragon, or dried herbes de Provence or dried thyme); 1/4 teaspoon kosher salt; 5 eggs; 8 ounces (1 cup) small curd cottage cheese (can use ricotta if you prefer); 2 tablespoons all-purpose flour (omit for gluten-free version); 1/2 teaspoon baking powder; 1 cup Parmesan cheese , grated; Fresh chives or parsley , chopped, for garnish