5-Ingredient Costco Dinners: Dijon Sheet Pan Chicken with Roasted Potatoes and Spinach

Welcome to 5-Ingredient Costco Dinners: From Costco Cart to Table – a new recipe series where every dish is built (almost) entirely from Costco ingredients, comes together fast, and actually tastes like something you’d be proud to put on the table. No stress, no fancy technique, no 47-step instructions. Just good food.

This is Recipe #1 – and it’s a great place to start. One pan, 40 minutes, and a Dijon mustard trick that makes people think you actually know what you’re doing in the kitchen.

The Costco97 Pantry Staples

Every recipe in this series assumes you’ve got a few basics on hand. These don’t count toward the 5 ingredients – they’re just things we think every Costco kitchen should have going at all times:

• Kirkland Signature Extra Virgin Olive Oil
• Kirkland Signature Himalayan Pink Salt
• Black pepper
• Christopher Ranch Colossal Fresh Garlic (the 2 lb bag in the produce section) – buy it, use what you need, freeze the rest in a zip bag. Frozen garlic cloves go straight from freezer to cutting board and taste just as good as fresh.
• Kirkland Signature Grass-Fed Butter (or regular KS Salted Butter if your location doesn’t carry the grass-fed version)

Your 5 Costco Ingredients

1. Kirkland Signature Boneless Skinless Chicken Thighs – thighs are the right call here, full stop. They stay juicy even if you get distracted. Breasts will dry out and you’ll be sad.
2. Kirkland Signature Baby Potatoes – the mixed color ones from the produce section. Small, fast-roasting, and they look great on the pan.
3. Kirkland Signature Organic Baby Spinach – yes, spinach on a sheet pan. It sounds wrong and works perfectly. Trust it.
4. Fresh lemons – just one. You’ll use both the zest and the juice and it ties the whole dish together. Costco sells them by the bag so you’ll have plenty left for your water, your cocktail, whatever.
5. Grey Poupon Dijon Mustard – this is the ingredient that makes people ask what your secret is. You’re going to rub it all over the chicken before it goes in the oven and it forms this incredible savory, slightly tangy crust that keeps everything juicy underneath. Pick it up at Costco if your location carries it – otherwise it’s at every grocery store. Either way, keep a jar in the fridge permanently.

🍌 The Cheat – Want to Take It Over the Top?

Scatter a big handful of pitted kalamata olives over the pan in the last 10 minutes of cooking. They get warm and slightly jammy in the oven and add a briny, Mediterranean hit that makes this feel like a completely different – and much more impressive – dish. Grab them at Costco if your location carries them, or any grocery store. Either way they’re worth keeping around.

Let’s Do This

Crank your oven to 425°F. Hot oven, crispy results – that’s the whole deal.

Smash 5 or 6 garlic cloves with the flat side of a knife until they crack open. Cut the baby potatoes in half and dump them onto a large sheet pan with the smashed garlic. Pour over a generous glug of olive oil, a good pinch of salt, and plenty of black pepper. Use your hands to toss everything together until the potatoes are well coated – yes your hands, it’s faster and more fun. Spread them out cut-side down in a single layer. If they’re piled on top of each other they’ll steam instead of roast. Into the oven for 15 minutes.

While the potatoes get a head start, pat the chicken thighs dry with a paper towel. This takes 10 seconds and makes a real difference – wet chicken steams, dry chicken browns. Zest the lemon over the thighs, then squeeze over about half the juice. Season generously with salt and pepper. Now spread a thin but confident layer of Dijon over the top of each thigh – use the back of a spoon and don’t be shy. You want every bit of that surface covered.

Pull the pan out after 15 minutes and give the potatoes a quick toss. Nestle the chicken thighs among them, mustard-side up. Squeeze the remaining lemon half over everything. Back in the oven for 20 to 25 minutes until the chicken is cooked through and the mustard crust is deeply golden and fragrant.

Pull the pan out, pile the baby spinach right on top – it looks like way too much but wilts down to almost nothing in 2 minutes – and slide it back in just until the spinach is wilted and glossy. Serve straight from the pan.

Happy Accident

Mustard crust not as golden as you’d like when the chicken is cooked through? Hit it under the broiler for 2 to 3 minutes at the end – don’t walk away though, broilers move fast. If the garlic cloves get very dark and caramelized that’s not a mistake, that’s a bonus – they turn sweet and jammy and are delicious spread onto the chicken or potatoes.

Try It These Ways Too

• Swap the veg: Costco’s baby bell peppers cut in half, or the big bag of broccoli florets both work beautifully. With broccoli, add it at the same time as the chicken since it roasts faster than potatoes.
• Swap the protein: Kirkland salmon fillets with the same Dijon and lemon treatment are outstanding. Add the salmon to the pan at the same time as the spinach – salmon only needs 12 to 15 minutes at 425°F and you really don’t want to overcook it.

Nutrition (Per Serving, Approx.)

Calories: 540 | Protein: 43g | Carbohydrates: 28g | Fat: 27g | Saturated Fat: 6g | Fiber: 5g | Sodium: 780mg

Approximate values. The Dijon adds negligible calories but an unreasonable amount of flavor.