Cheese toasties are a classic comfort food, but if you want to take them to the next level, you might want to try adding an 'unlikely' ingredient to the outside. It's mayonnaise! Yes, you heard that right. One Reddit user swore off butter forever after trying mayonnaise on their grilled cheese. They discovered that mayonnaise not only cooks the bread better and gives it a nicer color, but it also makes a better sandwich all around. The user even made a garlic mayonnaise spread for extra flavor. Another tip shared was to grate Parmesan cheese over the sandwich and pat it in to ensure it sticks. This creates a crispy crust on the outside and adds a satisfying crunch to the bite. Some users also suggested cooking cheese toasties in the oven instead of a pan. One user even recommended frying fish in fat-free mayonnaise for a healthier alternative. However, not everyone is a fan of mayonnaise. One user preferred the taste of butter and continued to use it on their cheese toastie. They combined Arnold healthnut bread, butter, Hellman's mayonnaise, Swiss cheese, and black garlic for a unique and delicious creation. The result was a mouth-watering sandwich that they topped with flaky salt. So, the next time you're making a cheese toasty, give mayonnaise a try and see if it takes your comfort food to a whole new level!