Adjust an oven rack to the upper-middle position and heat the oven to 400 degrees F. In a large bowl, lightly beat the eggs. Stir the Parmesan, feta, dill, and a light sprinkling of salt and pepper into the beaten eggs.

Heat the oil and the garlic in a 10-inch ovenproof nonstick skillet over medium-high heat. When the garlic sizzles and starts to turn golden, add the arugula. Cook the arugula, stirring constantly, until wilted, 1 to 2 minutes. Season lightly with salt and pepper. Reduce the heat to low, shaking the pan to distribute the arugula evenly. Add the egg mixture and cook until the eggs start to set around the edges, about 1 minute.

Transfer the pan to the oven and bake until the eggs are puffed and set, 10 to 12 minutes. Slide or invert the frittata onto a large plate, cut into four wedges and serve.