Vegetable Quiche

Ingredients

• Dough for single-crust pie
• 1 tablespoon butter
• 1 small red onion, halved and thinly sliced
• 1/2 cup sliced fresh mushrooms
• 1/4 cup finely chopped yellow summer squash
• 1/2 cup fresh baby spinach
• 3 garlic cloves, minced
• 1 cup shredded Swiss cheese
• 4 large eggs, lightly beaten
• 1-2/3 cups heavy whipping cream
• 1/2 teaspoon salt
• 1/2 teaspoon minced fresh rosemary
• 1/4 teaspoon pepper