I set out to make the perfect vegetarian cheese panini filling and this is the result! Packed with flavor and lots of melty, smoky, cheesy filling, it’s a panini recipe that everyone can enjoy.

I set out to make the perfect vegetarian cheese panini filling and this is the result! Packed with flavor and lots of melty, smoky, cheesy filling, it's a panini recipe that everyone can enjoy.

Hands up if you’ve ever been served a disappointing vegetarian panini?

I find that the packaged bread sold as panini bread in the supermarkets can be on the bland side, so if you don’t cram it full of intensely tasty filling, the overall effect will just be… blandness. Especially if the filling is less than generous.

Clearly, this does not apply in Italy, where the bread is different and every panino is absolute perfection, but if you’re working with the packed supermarket goods, you gotta compensate and just load it up with strong flavors.

In this cheese and onion panini recipe, we need our cheese and onions to work a lot harder, and that is something we can do fairly easily. Every one of the ingredients is a little bit elevated:

  • The bread is coated in dijon mustard which is a big cheese amplifier.
  • The cheese is a punchy smoked cheddar (with melty, oozy mozzarella for texture)
  • The onions are caramelized. We all know that is best.

Result? A rich filling which is nicely offset by the thick, crispy bread, without being drowned out. Just try drowning out this crazy, gooey mix of All Things Umami.

This is not your average cheese panini!

The panini in these photos is messy, indeed. I don’t even know what’s going on. Unless you’re an expert at containing filling in sandwiches (I am 100% not one) you may find that there is melted cheese and stray bits of onion dripping out the sides of yours. And you may stare quizzically at it for a few moments, wondering what your best move is going to be.

Don’t overthink it. Pick it up and tuck in!

This is not your average cheese panini!

Smoky Cheese & Caramelized Onion Panini

I set out to make the perfect vegetarian cheese panini filling and this is the result! Packed with flavor and lots of melty, smoky, cheesy filling, it’s a panini recipe that everyone can enjoy.
4.84 from 12 ratings

Ingredients

  • 2 panini breads
  • 2 red onions, thinly sliced
  • 1 Tbsp butter
  • ½ Tbsp mayonnaise or additional butter
  • 2 tsp dijon mustard
  • 75 g (2.65 oz) smoked cheddar cheese, grated
  • 75 g (2.65 oz) fresh mozzarella, thinly sliced

Instructions 

  • First, caramelize the onions. On a very low heat- the lowest your hob can manage- melt the butter into a pan and stir in the onions. Leave for around 30 minutes to 1 hour (It really depends on how low your heat can go- the lower the heat, the slower they will cook. You want it as slow as possible for a good flavor and texture.)
  • Slice the paninis, and spread with mayo and mustard.
  • Add the fillings in this order: 2/3rds of the smoked cheddar, mozzarella, red onions, remaining 1/3rd of the smoked cheddar.
  • Seal panini and press in a grill or frying pan until the cheese is melted. You can brush the outsides with oil to get extra crispiness but it’s not required.

Notes

I used paninis from Costco. They’re a bit smaller than the usual ones you get in cafes. I’m not sure whether they are the same as the ones in the US or Canadian Costcos. In any case, you may wish to scale up the ingredients if you think your paninis are a little bigger.
Serving: 1g, Calories: 541kcal, Carbohydrates: 43g, Protein: 24g, Fat: 30g, Saturated Fat: 16g, Polyunsaturated Fat: 3g, Monounsaturated Fat: 8g, Trans Fat: 1g, Cholesterol: 84mg, Sodium: 907mg, Potassium: 295mg, Fiber: 3g, Sugar: 5g, Vitamin A: 812IU, Vitamin C: 8mg, Calcium: 533mg, Iron: 1mg