Quick Recipe Version (TL;DR)
Quick Ingredients
- 6 medium sweet onions (about 8 oz / 225 g each), peeled
- 1 tbsp olive oil
- 1 tsp kosher salt, divided
- 1/2 tsp black pepper, divided
- 3 tbsp unsalted butter, melted
- 1 small garlic clove, finely grated
- 2 tbsp finely chopped parsley
- 1 tbsp finely chopped chives
- 1 tsp fresh thyme leaves (or 1/2 tsp dried)
- 1 cup (4 oz / 115 g) shredded sharp cheddar cheese
- 1/4 cup (1 oz / 28 g) finely grated Parmesan cheese
- 2 tbsp sour cream
Do This
- 1. Heat grill for indirect cooking to 400°F (204°C).
- 2. Brush peeled onions with olive oil; season with 1/2 tsp salt and 1/4 tsp pepper. Wrap each in foil.
- 3. Grill onions over indirect heat, covered, 50–60 minutes until very tender.
- 4. Unwrap; cut off the top 1/2 inch. Scoop out centers, leaving 2 outer layers intact; chop scooped onion.
- 5. Mix chopped onion with melted butter, garlic, herbs, cheddar, Parmesan, sour cream, remaining salt and pepper.
- 6. Stuff filling back into onion shells; place in a grill-safe pan.
- 7. Grill (still covered) 8–12 minutes at 425°F (218°C) until cheese bubbles; rest 5 minutes and serve.
Why You’ll Love This Recipe
- Sweet, jammy grilled onion meets a bubbling cheese-and-herb center (simple ingredients, big payoff).
- Looks impressive on a BBQ spread, but the method is straightforward and forgiving.
- Make-ahead friendly: roast the onions earlier, then stuff and finish on the grill right before serving.
- A naturally gluten-free side that pairs with everything from burgers to steak to grilled vegetables.
Grocery List
- Produce: 6 sweet onions, garlic, fresh parsley, fresh chives, fresh thyme
- Dairy: unsalted butter, sharp cheddar cheese, Parmesan cheese, sour cream
- Pantry: olive oil, kosher salt, black pepper
Full Ingredients
For the grilled onions
- 6 medium sweet onions (Vidalia or Walla Walla), about 8 oz / 225 g each, peeled
- 1 tbsp olive oil
- 1/2 tsp kosher salt
- 1/4 tsp black pepper
- 6 sheets heavy-duty aluminum foil (about 12 x 12 inches each)
For the cheesy herb stuffing
- 3 tbsp unsalted butter, melted
- 1 small garlic clove, finely grated or minced to a paste
- 2 tbsp finely chopped fresh parsley
- 1 tbsp finely chopped fresh chives
- 1 tsp fresh thyme leaves (or 1/2 tsp dried thyme)
- 1 cup (4 oz / 115 g) shredded sharp cheddar cheese
- 1/4 cup (1 oz / 28 g) finely grated Parmesan cheese
- 2 tbsp sour cream
- 1/2 tsp kosher salt
- 1/4 tsp black pepper
Optional finishing touches
- Extra chopped chives or parsley, for serving
- Freshly ground black pepper, for serving
Step-by-Step Instructions
Step 1: Set up your grill for indirect heat
Preheat your grill to 400°F (204°C) with an indirect heat setup (one side lit, one side off for a gas grill; coals banked to one side for charcoal). Close the lid and let it fully preheat.
This first phase is all about slowly softening and sweetening the onions without scorching the outside.
Step 2: Oil, season, and wrap the onions
Trim only the scraggly root hairs if needed, but keep the root end intact (it helps the onion hold together). Leave the onions whole and peeled.
Brush each onion all over with olive oil, then season with 1/2 tsp kosher salt and 1/4 tsp black pepper total (a light, even sprinkle over all the onions).
Place each onion in the center of a foil sheet and wrap tightly to form a sealed packet. A tight seal traps steam, which makes the onions tender and easy to hollow later.
Step 3: Grill-roast until deeply tender and sweet
Place the foil-wrapped onions on the cool/indirect side of the grill. Close the lid and cook for 50–60 minutes, turning the packets once halfway through.
The onions are ready when a skewer slides in with very little resistance and the packets feel soft when gently squeezed with tongs.
Step 4: Hollow the onions (save the centers)
Carefully remove the packets and let them sit for 5 minutes so you don’t get hit with a blast of steam. Unwrap.
Cut about 1/2 inch off the top of each onion (the stem end). Using a spoon, scoop out the center layers, leaving 2 outer layers intact to form a sturdy onion “cup.”
Finely chop the scooped onion (you should have about 1 1/2 cups chopped cooked onion).
Step 5: Make the buttery herb-and-cheese filling
In a medium bowl, combine the chopped cooked onion with melted butter, garlic, parsley, chives, and thyme.
Stir in the cheddar, Parmesan, and sour cream. Season with the remaining 1/2 tsp kosher salt and 1/4 tsp black pepper.
The mixture should look creamy and scoopable. If it seems very loose (some onions release more moisture), let it sit for 2 minutes to thicken as the cheeses hydrate, then stir again.
Step 6: Stuff the onions securely
Spoon the filling back into each hollowed onion, packing it in and mounding it slightly on top. Place the stuffed onions into a grill-safe skillet or disposable foil pan so they don’t tip and so any melted butter stays with the onions.
Step 7: Grill until bubbling and lightly browned
Increase grill heat to 425°F (218°C) (still using mostly indirect heat). Place the pan of stuffed onions on the grill and close the lid.
Cook for 8–12 minutes, until the cheese is fully melted and bubbling. If you’d like a bit more browning on top, move the pan briefly toward more direct heat for the last 1–2 minutes, watching closely so the cheese doesn’t burn.
Remove from the grill and rest for 5 minutes. Garnish with extra herbs and a little black pepper, then serve warm.
Pro Tips
- Choose the right onions: Sweet onions (Vidalia/Walla Walla) get especially jammy and mild. Yellow onions work too, but will taste more savory and sharp.
- Don’t over-hollow: Leaving 2 outer layers keeps the onion sturdy and prevents blowouts when the filling bubbles.
- Use a pan on the grill: It keeps the onions upright and catches any buttery drips (which you can spoon over at serving).
- Seal the foil well: A tight packet equals tender onions. If the onions feel firm at 60 minutes, reseal and cook 10 more minutes.
- Control browning at the end: Bubbling cheese happens fast. The last 2 minutes are when things can go from golden to scorched.
Variations
- Smoky bacon-cheddar: Add 4 slices cooked bacon, finely chopped, and swap half the cheddar for smoked gouda.
- Mediterranean herb-feta: Replace cheddar with 3/4 cup (3 oz / 85 g) crumbled feta and add 1 tbsp chopped dill. Use lemon zest (about 1/2 tsp) in the filling.
- Spicy pepper jack: Use pepper jack instead of cheddar and add 1/4 tsp cayenne or 1 minced jalapeño (seeded) to the filling.
Storage & Make-Ahead
Make-ahead: Grill-roast the onions up to 24 hours ahead. Cool, cover, and refrigerate. When ready to serve, hollow, mix, and stuff (or stuff ahead as well), then finish on the grill at 425°F (218°C) until hot and bubbling, usually 12–16 minutes from chilled.
Storage: Refrigerate leftovers in an airtight container for up to 3 days.
Reheat: Warm in a covered skillet over low heat, or in a 350°F (177°C) oven for 15–20 minutes, until heated through. (Microwaving works, but the onions soften more and the top won’t stay as nicely browned.)
Nutrition (per serving)
Approximate, per 1 stuffed onion: 240 calories, 16 g fat (9 g saturated), 18 g carbohydrates (3 g fiber, 9 g sugar), 8 g protein, 420 mg sodium.
