Rinse the fresh green beans under cold water, then trim the ends. Blanch in boiling water for 2 minutes if a tender texture is preferred, then plunge into ice water.

Heat a large skillet over medium heat and add 2 tablespoons of olive oil. Once shimmering, add sliced mushrooms and sauté for 5-7 minutes.

Add the prepared green beans and minced garlic to the skillet. Cook for 3-5 minutes until green beans are bright and crisp-tender.

Mix everything in the skillet, seasoning with salt and pepper. Add unsalted butter if desired and stir until melted.

Transfer to a serving dish and garnish with parsley or chives before serving.