Serious French Onion Soup

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

A classic, deeply caramelized onion soup with a golden, toasted cheese topping, requiring careful attention to avoid burning the onions. This french-inspired soups ready in about 95 minutes pairs yellow onions, unsalted butter, olive oil for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 380 calories and feeds 4, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

★ 4.1 (14 ratings) Prep: 20 min Cook: 75 min Serves 4 French cuisine 380 cal/serving
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Ingredients

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Instructions

  1. Step 1: Melt 2 tbsp butter and 2 tbsp olive oil in a large heavy-bottomed pot over medium heat. Add the sliced onions and sugar, then cook for 40-50 minutes, stirring every 5 minutes, until the onions are deeply caramelized and golden brown — do not rush the process to avoid burning.
  2. Step 2: Pour in the dry white wine and stir to deglaze the pot, scraping up any browned bits. Simmer for 5 minutes until the wine has evaporated.
  3. Step 3: Add the beef broth, thyme, bay leaves, salt, and pepper. Bring to a simmer, then reduce heat to low and cover. Simmer for 30 minutes to meld the flavors.
  4. Step 4: Preheat the broiler. Place the baguette slices on a baking sheet and toast under the broiler for 2-3 minutes until golden on both sides.
  5. Step 5: Ladle the soup into oven-safe bowls, top each with a toasted baguette slice, then sprinkle generously with 1/2 cup Gruyère and 2 tbsp Parmesan. Broil for 2-3 minutes until the cheese is bubbly and golden.

Frequently asked questions

How long does Serious French Onion Soup take to make?

Total time is about 95 minutes (20 min prep + 75 min cook). Most home cooks find this fits comfortably into a weeknight; double the batch on Sunday for two dinners.

How do I store leftover Serious French Onion Soup?

Cool to room temperature within 2 hours, then store in an airtight container in the fridge for up to 4 days. Reheat covered in a 350°F oven for 10-12 minutes, or microwave at 70% power in 60-second bursts to keep yellow onions from drying out.

Can I substitute ingredients in Serious French Onion Soup?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale Serious French Onion Soup for a different number of people?

The recipe is written for 4 servings. Multiply each ingredient by (your serving target / 4). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with Serious French Onion Soup?

French soups like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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