Heat the Pan: Add the extra virgin olive oil and unsalted butter to a large, heavy skillet set over medium-high heat. Allow the butter to melt and foam gently.
Sear the Mushrooms: Arrange the halved cremini mushrooms in a single, un-crowded layer across the skillet. Let them cook undisturbed for 3 to 4 minutes until a deep golden-brown crust forms on the bottom.
Toss and Sauté: Turn the mushrooms over and cook for another 3 minutes until they shrink slightly and brown evenly on all sides.
Incorporate Aromatics: Lower the skillet heat to medium. Add the thinly sliced garlic cloves, julienned sun-dried tomatoes, and red pepper flakes. Cook for 1 to 2 minutes, stirring continuously to prevent the garlic from burning.
Season: Season the mixture generously with salt and freshly cracked black pepper, tossing well to coat the mushrooms in the light pan sauce.
Garnish and Serve: Turn off the heat. Throw in the finely chopped fresh parsley, tossing well so the residual skillet heat gently wilts the herbs before serving.