Slow-Caramelized Onion Soup with Gruyère and Thyme
A deeply aromatic French soup featuring onions caramelized to golden perfection, simmered in rich broth, and topped with melted Gruyère for a comforting, traditional experience. This french-inspired soups ready in about 80 minutes pairs unsalted butter, large, thinly sliced yellow onion, all-purpose 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.
Ingredients
- 2 tbsp unsalted butter
- 1 large, thinly sliced yellow onion
- 1 tbsp all-purpose flour
- 4 cups beef broth
- 1/4 cup dry red wine
- 1 sprig fresh thyme
- 1/2 tsp salt
- 1/4 tsp black pepper
- 1 cup, grated Gruyère cheese
- 1, sliced into 1/2-inch thick pieces baguette
Instructions
- Step 1: Melt 2 tbsp unsalted butter in a large pot over medium-low heat. Add 1 large yellow onion, thinly sliced, and cook for 45-50 minutes, stirring occasionally, until deeply golden brown and caramelized.
- Step 2: Sprinkle 1 tbsp all-purpose flour over the onions and stir for 1 minute until combined and no raw flour taste remains.
- Step 3: Add 4 cups beef broth, 1/4 cup dry red wine, 1 sprig fresh thyme, 1/2 tsp salt, and 1/4 tsp black pepper. Bring to a gentle simmer and cook for 20 minutes.
- Step 4: Remove the thyme sprig, ladle the soup into 4 oven-safe bowls, and top each with 1/4 cup grated Gruyère cheese and 2 slices of baguette.
- Step 5: Broil on high for 3-5 minutes until the cheese is golden and bubbly.
Equipment for this recipe
Top-rated tools to make this recipe successfully.
Frequently asked questions
How long does Slow-Caramelized Onion Soup with Gruyère and Thyme take to make?
Total time is about 80 minutes (20 min prep + 60 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 Slow-Caramelized Onion Soup with Gruyère and Thyme?
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 unsalted butter from drying out.
Can I substitute ingredients in Slow-Caramelized Onion Soup with Gruyère and Thyme?
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 Slow-Caramelized Onion Soup with Gruyère and Thyme 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 Slow-Caramelized Onion Soup with Gruyère and Thyme?
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.
What others are saying
- ★★★★★
This is the best onion soup I've ever made! The Gruyère melted into a golden blanket.
- ★★★★☆
The onions were perfect, but the soup was slightly bland—added extra thyme and a splash of wine next time.
- ★★★★☆
Took longer than expected to caramelize the onions, but the deep flavor was worth the wait.
