Spinach, Mushroom and Onion Omelette - Eggs.ca

Ingredients

• 1 tbsp oil
• 1 cup cremini mushrooms, thinly sliced
• 1 medium onion, sliced
• 1/2 tsp kosher salt, divided
• 1/2 tsp black pepper, divided
• 2 cups fresh baby spinach
• 5 large eggs
• 1/2 cup shredded Gruyere cheese
• 2 tbsp butter, divided
• Minced fresh parsley, for garnish