Low-and-Slow Caramelized Onion Soup

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

Deeply sweet onions simmered for 45 minutes to create a rich, velvety soup base with no added sugar. This french-inspired soups ready in about 95 minutes pairs onions, butter, chicken stock for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 220 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.

★ 4.3 (12 ratings) Prep: 20 min Cook: 75 min Serves 4 French cuisine 220 cal/serving
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Ingredients

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Instructions

  1. Step 1: Melt 2 tbsp butter in a heavy-bottomed pot over medium-low heat. Add 4 medium thinly sliced onions and cook for 10 minutes, stirring occasionally, until they begin to soften.
  2. Step 2: Reduce heat to low and cook for 45 minutes, stirring every 10 minutes, until onions are golden brown and caramelized—do not rush or they will burn.
  3. Step 3: Stir in 3 cups chicken stock and 1 tsp fresh thyme, then bring to a gentle simmer and cook uncovered for 20 minutes.
  4. Step 4: Remove from heat and stir in 1/4 cup heavy cream and 1/4 tsp salt until fully incorporated and the soup is smooth.
  5. Step 5: Let rest for 5 minutes before serving to allow flavors to meld.

Frequently asked questions

How long does Low-and-Slow Caramelized 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 Low-and-Slow Caramelized 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 onions from drying out.

Can I substitute ingredients in Low-and-Slow Caramelized 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 Low-and-Slow Caramelized 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 Low-and-Slow Caramelized 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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