Cauliflower and Caramelized Onion Tart

Ingredients

• 1 head cauliflower about 1 pound or 1 pound of a larger head of cauliflower, cut into 1-inch flowerets, Romanesco cauliflower, especia…
• 3 1/2 tablespoons olive oil
• 1 tablespoon truffle oil optional
• 3 pinches truffle salt optional
• 1 refrigerated pie crust or a homemade tart shell, recipe below
• 1 onion large, halved lenghtwise and thinly sliced
• 1 tablespoon Dijon mustard
• 2 large eggs
• 1 mascarpone cheese 7- to 8- ounce container, see Note below for suggested substitutions
• 1/2 cup whipping cream although any low- or full-fat milk or light cream will work as well
• 1/4 teaspoon black pepper or ground white
• 1 pinch ground nutmeg
• 1 cup grated Gruyère cheese Swiss or Comté are great swaps
• 1/3 cup Parmesan cheese
• 1 1/4 cups flour
• 1 tablespoon cornstarch
• 1/4 teaspoon salt
• 6 tablespoons butter diced
• 1 egg

Nutrition

• Calories : 570 calories
• Carbohydrate : 37 grams
• Cholesterol : 150 milligrams
• Fat : 40 grams
• Fiber : 3 grams
• Protein : 15 grams
• SaturatedFat : 19 grams
• Sodium : 620 milligrams
• Sugar : 3 grams