Grilled Cheese With Marmite and Caramelized Onions

The British condiment delivers umami in every bite of this satisfying sandwich.

Makes
2 sandwiches
Time
1 hour

PHOTO: MURRAY HALL • FOOD STYLING: BEN WEINER

Published on March 12, 2026

In this American twist on the classic British toastie, grated cheese and caramelized onions combine with Marmite to form the centerpiece of a truly moreish grilled cheese sandwich—coating the bread in Marmite butter brings umami to every bite. Serve with a side of tangy pickles to balance the rich flavors.

Featured in “Why Marmite Deserves a Place in Your Pantry.”

Ingredients

For the Marmite butter:

2 Tbsp. unsalted butter, softened
¼–½ tsp. Marmite

For the sandwich:

2 Tbsp. unsalted butter
1 Tbsp. olive oil
1 medium onion, coarsely chopped
1 tsp. packed Marmite
4 oz. sharp cheddar, coarsely grated
4 slices sandwich bread, preferably white or rye
1 Tbsp. lus 1 tsp. Dijon mustard

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Instructions

Step 1

Make the Marmite butter: To a small bowl, add the butter and the Marmite to taste and stir with a silicone spatula or spoon until completely blended. Set aside.

Step 2

Make the sandwich: To a large skillet over medium-high heat, add the butter and oil. When the butter melts, add the onion and stir to coat, then turn the heat to medium-low. Cook, stirring occasionally, until the onion begins to soften and turn golden, 15–20 minutes. Stir in the Marmite and continue cooking until fragrant and golden brown, 5–10 minutes more. Remove from the heat and set aside to cool to room temperature, then stir in the cheddar (The cheese and onion filling can be refrigerated, covered, for up to 1 week).

Step 3

Spread each slice of bread with 1 teaspoon of the mustard, then divide the filling equally between 2 slices of the mustard-coated bread, spreading it evenly across the surfaces. Top with another slice of bread mustard-side down, then coat the outside of each piece of bread with 1 teaspoon of the Marmite butter.

Step 4

To a large skillet over medium heat, add the sandwiches, pressing down softly with the back of a spatula. Cook until golden and lightly toasted, 3–4 minutes, then flip and cook on the other side, pressing down again with the spatula, until toasted and the filling is beginning to ooze out of the sides, 2–3 minutes more. Transfer each sandwich to a plate, cut in half, and serve immediately.

Make the Marmite butter: To a small bowl, add the butter and the Marmite to taste and stir with a silicone spatula or spoon until completely blended. Set aside.
Make the sandwich: To a large skillet over medium-high heat, add the butter and oil. When the butter melts, add the onion and stir to coat, then turn the heat to medium-low. Cook, stirring occasionally, until the onion begins to soften and turn golden, 15–20 minutes. Stir in the Marmite and continue cooking until fragrant and golden brown, 5–10 minutes more. Remove from the heat and set aside to cool to room temperature, then stir in the cheddar (The cheese and onion filling can be refrigerated, covered, for up to 1 week).
Spread each slice of bread with 1 teaspoon of the mustard, then divide the filling equally between 2 slices of the mustard-coated bread, spreading it evenly across the surfaces. Top with another slice of bread mustard-side down, then coat the outside of each piece of bread with 1 teaspoon of the Marmite butter.
To a large skillet over medium heat, add the sandwiches, pressing down softly with the back of a spatula. Cook until golden and lightly toasted, 3–4 minutes, then flip and cook on the other side, pressing down again with the spatula, until toasted and the filling is beginning to ooze out of the sides, 2–3 minutes more. Transfer each sandwich to a plate, cut in half, and serve immediately.