Caramelized Onion and Blue Cheese Omelet

Quick Recipe Version (TL;DR)

• Yield: 2 servings
• Prep Time: 10 minutes
• Cook Time: 40 minutes
• Total Time: 50 minutes

Quick Ingredients

• 1 medium yellow onion, thinly sliced
• 2 tablespoons unsalted butter, divided
• 1 teaspoon extra-virgin olive oil
• 1/4 teaspoon fine sea salt, divided
• 1/4 cup chopped walnuts
• 6 large eggs
• 2 tablespoons water
• 2 ounces creamy blue cheese, crumbled
• 2 teaspoons fresh thyme leaves, divided
• 1/2 teaspoon freshly cracked black pepper

Do This

• 1. Toast the walnuts in a dry skillet over medium-low heat for 3 to 5 minutes.
• 2. Cook the onion with 1 tablespoon butter, the olive oil, and 1/8 teaspoon salt over medium-low heat for 25 to 30 minutes.
• 3. Whisk the eggs with the water and remaining 1/8 teaspoon salt.
• 4. Melt 1 1/2 teaspoons butter in an 8- or 9-inch nonstick skillet over medium-low heat.
• 5. Add half the eggs, gently draw the edges inward, and cook until softly set, 2 to 3 minutes.
• 6. Add half the onions, blue cheese, walnuts, thyme, and pepper to one side; fold and slide onto a plate. Repeat for the second omelet.
• 7. Garnish with the reserved thyme, walnuts, blue cheese, and black pepper; serve immediately.

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Why You’ll Love This Recipe

• Slow-cooked onions add deep sweetness that balances the tangy blue cheese.
• Toasted walnuts bring a warm, buttery crunch to every bite.
• Gentle heat keeps the eggs tender, soft, and delicately folded.
• The onions can be prepared ahead for an easy gourmet breakfast or brunch.

Grocery List

• Produce: 1 medium yellow onion and 1 small bunch fresh thyme
• Dairy: 6 large eggs, 2 ounces creamy blue cheese, and unsalted butter
• Pantry: Chopped walnuts, extra-virgin olive oil, fine sea salt, and whole black peppercorns

Full Ingredients

For the Caramelized Onions

• 1 medium yellow onion, about 8 ounces, halved and thinly sliced from root to stem
• 1 tablespoon unsalted butter
• 1 teaspoon extra-virgin olive oil
• 1/8 teaspoon fine sea salt
• 1 to 2 tablespoons water, only if needed to prevent sticking

For the Omelets

• 6 large eggs
• 2 tablespoons cool water
• 1/8 teaspoon fine sea salt
• 1 tablespoon unsalted butter, divided
• 2 ounces creamy blue cheese, crumbled and divided
• 1/4 cup chopped walnuts, toasted and divided
• 2 teaspoons fresh thyme leaves, divided
• 1/2 teaspoon freshly cracked black pepper, divided

For Serving

• Reserved crumbled blue cheese
• Reserved toasted walnuts
• Reserved fresh thyme leaves
• Additional freshly cracked black pepper, if desired

Step-by-Step Instructions

Step 1: Toast the walnuts

Place the chopped walnuts in a dry 8- or 9-inch nonstick skillet. Toast them over medium-low heat for 3 to 5 minutes, stirring frequently, until they smell nutty and develop a little golden color. Transfer the walnuts to a plate immediately so they do not continue to cook in the hot pan. Set aside 1 tablespoon for garnishing the finished omelets.

Step 2: Slowly caramelize the onion

Return the skillet to medium-low heat and add 1 tablespoon of the butter and the olive oil. When the butter has melted, add the sliced onion and 1/8 teaspoon salt. Stir until the onion is evenly coated, then spread it into a thin layer.

Cook for 25 to 30 minutes, stirring every 3 to 4 minutes. The onion should soften gradually before turning golden brown, glossy, and jammy. If the bottom of the skillet develops dark spots or the onion begins to stick, add 1 tablespoon water and scrape up the browned bits. Reduce the heat if the onion is browning before it becomes tender. Transfer the caramelized onion to a bowl and wipe out the skillet.

Step 3: Prepare the eggs and filling

Crack the eggs into a medium bowl. Add 2 tablespoons cool water and the remaining 1/8 teaspoon salt. Whisk for 30 to 45 seconds, until the whites and yolks are completely combined and the mixture is lightly frothy. The water creates steam as the eggs cook, helping the omelets stay tender.

Divide the caramelized onions, blue cheese, toasted walnuts, thyme, and black pepper into two equal portions. Reserve a small amount of cheese, walnuts, and thyme for the final garnish.

Step 4: Begin the first omelet

Place the clean skillet over medium-low heat and add 1 1/2 teaspoons butter. Swirl the skillet until the butter melts and lightly coats the bottom without browning. Pour in half of the egg mixture, about 3/4 cup.

Let the eggs sit undisturbed for 20 seconds. Using a silicone spatula, gently draw the cooked edges toward the center while tilting the skillet so the uncooked egg flows into the empty spaces. Continue for 1 to 2 minutes, working slowly to form soft, even curds.

Step 5: Add the filling

When the omelet is mostly set but still looks slightly moist and glossy on top, stop stirring. Arrange half of the caramelized onion over one side of the eggs. Sprinkle with half of the blue cheese, half of the walnuts, half of the thyme, and half of the cracked black pepper. Keep the filling about 1/2 inch away from the edge so the omelet will fold neatly.

Step 6: Fold and repeat

Use the spatula to loosen the unfilled side of the omelet, then gently fold it over the filling to form a half-moon. Cook for 20 to 30 seconds, just until the blue cheese begins to soften. Do not wait for all the cheese to melt; small creamy crumbles provide the best flavor and texture.

Tilt the skillet and slide the omelet onto a warm plate. Wipe the skillet clean, add the remaining 1 1/2 teaspoons butter, and repeat with the remaining egg mixture and filling.

Step 7: Garnish and serve

Top each omelet with the reserved blue cheese, toasted walnuts, and fresh thyme. Finish with additional cracked black pepper if desired. Serve immediately while the eggs are soft and warm and the blue cheese is creamy. A lightly dressed green salad, roasted breakfast potatoes, or toasted sourdough makes an excellent accompaniment.

Pro Tips

• Keep the onion slices even: Slices about 1/8 inch thick will soften and caramelize at roughly the same rate.
• Do not rush the onions: Medium-low heat develops sweetness without scorching. Proper caramelization takes at least 25 minutes.
• Choose a creamy blue cheese: Gorgonzola dolce is mellow and creamy, while Danish blue or Roquefort provides a sharper, saltier flavor.
• Cook one omelet at a time: A smaller omelet is easier to control, fill, and fold without tearing.
• Remove the eggs while glossy: Residual heat will finish cooking them after they leave the skillet, keeping the centers tender rather than dry.

Variations

• Apple and blue cheese: Add 1/4 cup of finely diced tart apple to the caramelized onions during their final 5 minutes of cooking.
• Mushroom and onion: Sauté 4 ounces of sliced cremini mushrooms until browned, then add them to the filling with the onions.
• Milder cheese option: Replace the blue cheese with 2 ounces of crumbled goat cheese or shredded aged white cheddar.

Storage & Make-Ahead

The caramelized onions can be prepared up to 4 days in advance and refrigerated in an airtight container. Reheat them gently in a skillet over low heat before assembling the omelets. Toasted walnuts can be stored in an airtight container at room temperature for up to 1 week. For the best texture, cook the omelets just before serving. Leftover cooked omelets may be refrigerated within 2 hours in an airtight container for up to 2 days. Reheat them, covered, in a 275°F oven for 8 to 10 minutes, or microwave at 50% power in 30-second intervals until the center reaches 165°F. Freezing is not recommended because the eggs may become watery and rubbery.

Nutrition (per serving)

Calories: 560 kcal | Carbs: 8g | Protein: 28g | Fat: 46g | Saturated Fat: 18g | Fiber: 2g | Sugar: 3g | Sodium: 830mg | Cholesterol: 610mg