Preheat oven to 350°.
Spray a 13x9x2 inch baking dish with cooking spray.
In a sauté pan, heat olive oil over medium high heat.
Add fresh mushrooms and sauté until brown, about 10 minutes.
Add sherry and cook until sherry has evaporated. Add tarragon and salt and pepper.
In a medium bowl, add eggs, half & half, a pinch of salt and pepper and beat.
Arrange half of the King’s Hawaiian rolls on the bottom of the baking dish.
Top with the mushrooms and half of gruyere and Parmesan cheese. Then top with the other half of the rolls.
Drizzle the egg mixture over the rolls. Sprinkle the remaining cheese over the egg mixture.
Bake uncovered for 40 minutes or until golden brown.