Preheat your oven to 400°F / 205°C. Prepare your vegetables: finely shred the cabbage, dice the onion, and slice the mushrooms.
In a large frying pan, melt the butter over medium heat.
Add the cabbage, onion, and mushrooms and sauté for 3–5 minutes until softened.
Stir in the salt, pepper, basil, marjoram, and tarragon.
Mix well to combine, then remove the pan from the heat.
Assemble the pie: Gently press one piecrust into the bottom of your pie pan.
Spread the softened cream cheese evenly across the crust.
Arrange the sliced hard-boiled eggs over the cream cheese, then sprinkle the fresh dill on top. Spoon the sautéed vegetable mixture over the eggs.
Place the second piecrust on top. Trim any excess crust that hangs over the edge of the pan. Crimp the edges of the top and bottom crusts together to seal the pie.
Using a sharp knife, cut a few small slits in the top crust to allow steam to escape during baking.
Bake for 15 minutes.
Then, reduce the oven temperature to 350°F / 180°C and continue baking for another 20-25 minutes, or until the crust is golden brown.
Let rest briefly before serving.
