Cheesy Mustard Recipe

Prep and cook potatoes

Peel the russet potatoes and cut into uniform 1–2 inch (2–5 cm) cubes so they cook evenly. Place potatoes in a large saucepan and cover with cold water by about 1 inch (2.5 cm). Add 1/2 tsp of the salt. Bring to a boil over high heat, then reduce to a simmer and cook until very tender when pierced with a fork, about 15–20 minutes depending on cube size.

Warm milk and butter

While potatoes cook, gently warm the milk, 3 tbs butter, and optional cream in a small saucepan over low heat until the butter is melted and milk is warm but not boiling. Warming prevents cooling the potatoes and helps produce a silkier mash.

Drain and dry

When potatoes are tender, drain thoroughly in a colander and return to the hot pot. Place the pot back on the stove over very low heat for 30–60 seconds, shaking the pot gently to evaporate excess moisture — this step helps produce fluffy mash.

Mash and season

Using a potato ricer or masher, mash the potatoes to your desired texture. Gradually add the warmed milk and butter mixture, stirring until incorporated and smooth. Season with the remaining 1 tsp salt and 1/2 tsp black pepper, tasting and adjusting seasoning as needed. If you want extra richness, stir in the optional 2 tbs cream now.

Combine cheese and mustards

In a bowl, mix the grated mature cheddar with the whole grain mustard and optional Dijon mustard until evenly combined. The cheddar should be at room temperature or freshly grated so it melts into the hot mash more easily.

Fold cheese into mash

With the mashed potatoes hot, fold in about three-quarters of the cheesy mustard mixture, stirring gently but thoroughly until the cheese is melted and evenly distributed. Taste and add more of the mixture if you want a stronger mustard-cheddar flavor. If the mash feels too stiff, add up to 1–2 tbs additional warm milk.

Finish and garnish

If using, stir in the final 1 tbs butter for a glossy finish. Transfer the cheesy mustard mash to a serving dish and sprinkle the reserved cheese mixture over the top for visible cheddar and mustard seeds. Garnish with finely chopped chives. Serve immediately while hot.