1) Position an oven rack 15cm below the grill and preheat.
2) Heat a large heatproof nonstick skillet over medium-high heat, add the olive oil. Add the mushrooms, tossing briefly, and then cook until browned, about 12 to 15 mins. Toss in the spring onions once the mushrooms begin to brown, about 2/3 of the way of cooking. Stir in 40g parsley and tarragon.
3) Meanwhile, whisk the eggs with the mushroom and season with salt and pepper. Sprinkle in gorgonzola and stir gently to combine.
4) Reduce heat to medium and pour the eggs into the skillet, stirring gently so that the mushrooms and herbs are evenly distributed. Continue cooking and gently stirring until the eggs begin to set, about 4 mins.
5) Place skillet under the grill and cook until the frittata is set, about 3 to 4 mins. Slide frittata out of skillet if desired, sprinkle with remaining tbsp parsley, and cut into wedges.
* Cook's note: There are prepared mushroom broths on the market. If you can't find one, make your own with a bit of dried mushrooms. Simply heat a 500ml water with a healthy pinch of dried mushrooms, like porcini, or shiitake, or a mixture. Steep until flavourful. Strain and reserve the liquid. Use the hydrated mushrooms as desired.