Old-Fashioned French Onion Soup

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

A soul-warming classic where onions are slowly caramelized to deep golden perfection, then simmered in rich broth and topped with melty cheese for an authentic French bistro experience. This French-inspired soup recipe, ready in about 65 minutes, pairs Yellow onions, Butter, Flour for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 320 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.

Prep: 20 min Cook: 45 min Serves 4 French cuisine 320 cal/serving
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Ingredients

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Instructions

  1. Step 1: Melt 4 tbsp butter in a large pot over medium-low heat. Add 3 lbs thinly sliced yellow onions and cook for 45-50 minutes, stirring occasionally, until deeply golden brown and caramelized — this slow process is essential for flavor.
  2. Step 2: Sprinkle 2 tbsp flour over onions and stir for 1 minute to cook off raw taste. Add 1/2 cup white wine and simmer for 5 minutes until wine reduces by half.
  3. Step 3: Add 4 cups beef broth, 2 sprigs thyme, 1 bay leaf, 1 tsp salt, and 1/2 tsp black pepper. Bring to a gentle simmer and cook uncovered for 20 minutes to meld flavors.
  4. Step 4: Remove thyme and bay leaf. Ladle soup into oven-safe bowls, top each with 1 toasted baguette slice, and sprinkle with 1/4 cup grated Gruyere cheese. Broil for 2-3 minutes until cheese is bubbly and golden brown.

Frequently asked questions

How long does Old-Fashioned French Onion Soup take to make?

Total time is about 65 minutes (20 min prep + 45 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 Old-Fashioned 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 Old-Fashioned 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 Old-Fashioned 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 Old-Fashioned 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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