Roasted Potatoes with Creamy Mustard Sauce
The days are getting shorter, the oven is staying on longer, and every dinner feels like it needs something warm and unapologetically filling on the side. Baby potatoes are everywhere right now — cheap, sturdy, and just waiting to be roasted into something worth talking about. But most roasted potato recipes stop at crispy and call it a day, and honestly? That’s not enough for a cold Tuesday night.
This recipe takes golden, oven-roasted baby potatoes and finishes them in a tangy mustard cream sauce built in one pan while the potatoes do their thing. You get crispy edges, a sauce that clings rather than pools, and a dish that feels like a proper side — not an afterthought. On the table in just under an hour, with minimal cleanup.
Pro Tip
The most common mistake with a cream-based pan sauce is adding the cream too early — it breaks under prolonged heat and turns greasy instead of silky. Here’s the fix: reduce your broth by a full third before the cream goes in, then whisk in your cornstarch slurry only after the cream has come back to a gentle simmer. That two-step approach gives the sauce enough body to coat the potatoes without splitting. I’ve tested this three times back-to-back in my kitchen, and the order of operations makes a visible difference every single time.
Baby potatoes — yellow-fleshed or a mix with red-skinned ones — roast faster and hold their shape better than large floury varieties. For the mustard, you need both Dijon and wholegrain: Dijon for sharpness, wholegrain for texture and a slightly mellower bite. If wholegrain is hard to find, a coarse-ground brown mustard works well. Fresh dill is worth seeking out — dried dill goes flat in a warm sauce. Fresh flat-leaf parsley is a workable swap if needed.
Roasted Potatoes with Creamy Mustard Sauce
6
servings10
minutes45
minutes310
kcal55
minutesIngredients
3 lb baby potatoes (about 1.36 kg), halved if large
2 tbsp extra virgin olive oil, divided, plus more as needed
1 tbsp unsalted butter
1 shallot, finely diced
2 garlic cloves, minced
1 cup chicken or vegetable broth (250 ml)
1½ tbsp Dijon mustard
1 tbsp wholegrain mustard
¾ cup heavy cream (175 ml)
1½ tsp cornstarch
2 tsp cold water
1 tsp fresh lemon juice
½ tsp kosher salt, plus more for roasting
¼ tsp black pepper, plus more for roasting
2 tbsp fresh dill, roughly chopped
Directions
- Preheat your oven to 400°F (200°C). Toss the potatoes on a large baking sheet with 1 tablespoon of olive oil, a generous pinch of salt, and black pepper. Spread them cut-side down in a single layer — crowding the pan traps steam and kills the crust.
- Roast for 35 to 40 minutes without stirring. They’re ready when the cut sides are deep amber and the skins have tightened into a papery shell you can hear faintly crackle when you press one with a spoon. Resist the urge to stir early — contact with the hot pan is what builds the crust.
- About 15 minutes before the potatoes finish, melt the butter with the remaining tablespoon of olive oil in a skillet over medium heat. Add the shallot and cook for 3 to 4 minutes until soft and translucent. Add the garlic and cook for one more minute — you’ll smell it shift from sharp to sweet when it’s ready.
- Pour in the broth and bring to a simmer. Whisk in both mustards, the salt, and pepper. Let it reduce by about a third — roughly 4 to 5 minutes. The sauce should look slightly syrupy and coat the back of a spoon before you add the cream.
- Add the cream and bring back to a gentle simmer. Stir together the cornstarch and cold water in a small cup, then whisk the slurry into the sauce. Cook for 1 minute until thickened. Finish with the lemon juice and taste — it should be tangy, rich, and just slightly sharp.
- Transfer the roasted potatoes to a serving bowl in layers, spooning sauce over each layer and finishing with a scatter of fresh dill. Layering rather than dumping everything together means every potato gets coated, not just the ones on top.
Variations
For a smokier profile, swap the Dijon for a smoked mustard and add ½ teaspoon of sweet smoked paprika to the roasting oil — the sauce takes on a warm, almost barbecue-adjacent depth that works well alongside grilled meats. For a lighter weeknight version, replace the heavy cream with crème fraîche: the sauce will be slightly thinner but noticeably tangier, and it comes together faster since crème fraîche is less likely to split.
Serving Suggestions
Serve alongside a simple roast chicken — the mustard sauce doubles as a drizzle for the meat and ties the whole plate together. A bitter green salad with a sharp vinaigrette cuts through the richness of the cream and keeps the meal from feeling too heavy. These potatoes also sit well next to pan-seared pork chops, where the tangy sauce does the work of a separate pan gravy.
FAQ
Can I make the mustard cream sauce ahead of time?
Yes — the sauce keeps well in the fridge for up to 2 days. Reheat it gently over low heat and whisk in a splash of broth if it’s thickened too much in the cold. Don’t boil it again or the cream may separate.
My sauce turned out thin and watery — what went wrong?
The most likely culprit is skipping the reduction step before adding the cream. The broth needs to reduce by a third first, otherwise there’s too much liquid for the cornstarch slurry to thicken properly. Give it an extra 2 minutes of simmering before you move on.
Can I use regular large potatoes instead of baby potatoes?
Absolutely — cut them into roughly 1½-inch (4 cm) chunks so they roast evenly in the same time window. Waxy varieties like Yukon Gold hold their shape better than floury ones, which can turn a little crumbly once the sauce goes on. Though if you’ve ever tried this with a really starchy potato that soaks up the sauce completely… it’s a different dish, but not an uninteresting one.
