The Science Behind Grilled Cheese

Colin Ji Teaches his Toasty Recipe


Beautifully browned, crispy slices of sourdough bread house three kinds of cheese. Photo by Colin Ji.

Colin Ji, Jessica Woo, and Alyssa Chang

Sniff, I smell a splash of fragrant grease up in the kitchen. I hear the sound of liquid making its partner crispy. I walk up to the spot-lighted pan and peer at the two beautiful slices of brea – Wait. What is this? I can sense the terrifying machines that processed chemicals in this… “grilled cheese.” 

Grilled cheese is a beginner-level dish. The sandwich’s simplicity – its minimal ingredients, short cooking time, and a procedure so easy it’s harder to mess it up – drives numerous home cooks to the pan on their stove. Nevertheless, I know that some of you have burnt the last slices of bread in your house to a lump of coal. 

To take this dish to another level, we need to understand it. A typical grilled cheese starts with some mass-manufactured bread, waxy American slices from factories hundreds of miles away, and butter. To balance flavors, use flavorful and smooth cheese and light, crispy bread. I chose sourdough and a mix of three kinds of cheese (mature cheddar, mozzarella, and pepper jack). 

A loaf of sourdough bread is one of the most time-consuming recipes in the whole baking world – but its unique fragrance makes the process worth it. To begin, you need to make a jar of Levain. You need 35g of mature sourdough starter, 35g of whole wheat flour, 35g of all-purpose flour, and 70g of room temperature water (around 25 degrees Celsius). 

The science of baking is primarily dependent on yeast, a single-celled microorganism that contributes to the leavening power and flavor of the dough by converting simple carbohydrates to carbon dioxide and ethanol. Stir together the ingredients in a small bowl and rest in a warm area (around 25 degrees Celsius) for 5 hours. As the yeasts feast on available sugars, the byproducts create gas bubbles.

The bubbles, trapped in a well-developed gluten matrix, expand the dough and create an airy, spongy loaf.

A sliced loaf of sourdough bread with air bubbles created by fermentation. Photo by Colin Ji.

Sourdough Bread Recipe

  1. One hour before the levain is done, make the dough. In a large bowl, mix the bread flour and whole wheat flour. Add 580g water to the flour mixture (keeping 100g to the side for mixing later).
  2. Mix just until your dough comes together. Cover with plastic wrap and let it rest in a warm area (21–27°C) for 1 hour.
  3. Mix your dough and levain, using a little of your water to help incorporate. Rest for 20 minutes.
  4. Add the sea salt and all of the remaining water and mix until incorporated. Slap and fold for 2 to 4 minutes or until your dough is smooth and begins to catch some air. Rest 15 minutes in the same warm area.
  5. Perform six sets of stretch and folds spaced out by 15 minutes for the first three, then 30 minutes for the last three. Place the dough back in the warm area for each rest.
  6. Let your dough rest for a final ½ hours, undisturbed.
  7. Dump out and divide your dough into two even pieces. Pre-shape each piece into a light boule and rest for 5 to 10 minutes.
  8. Shape each ball dough into a batard and place it into bannetons dusted with either rice flour or all-purpose flour.
  9. Refrigerate overnight.
  10. Preheat the cast-iron combo cooker to 260°C for 1 hour.
  11. Carefully place a dusted loaf into the hot pan, score the top, and set the larger lid on top. Bake for 20 minutes.
  12. Remove the top from the combo cooker and lower the oven temperature to 230°C. Bake for an additional 20 to 30 minutes, or until the loaf is a deep brown color.
  13. Remove the bread and cool on a wire rack until room temperature. Repeat with the other loaf.


As you can see, it’s a lengthy procedure. I recommend you start cooking on a peaceful weekend morning – I learned this the hard way after I had to stay awake overnight because I started at 9 pm.

Cheese comes next: I chose mature cheddar, for the classic cheesy flavor, and adhesive properties, while mozzarella adds a creamy texture and satisfying aftertaste. Last, I put pepper jack cheese to balance out the butter and grease.

What else makes grilled cheese so appealing? It’s the butter. Instead of cheap butter, try to use a well-made butter of your taste. I chose Isigny Sainte-Mere unsalted butter – this butter in this region is famous for its exceptionally fine milk and rich fat. 

To finish your grilled cheese:


Grilled Cheese Recipe

  1. Spread softened butter on one side of both slices of bread.
  2. Place it butter-side down on a cold pan, and start the stove to medium fire. 
  3. With a cheese grater or zester, grind the cheeses into a bowl and thoroughly mix them. 
  4. When the bread begins to get crispy but not yet brown, gently place the mix of cheeses on top of one slice of bread.
  5. Then, place the other slice on top (butter side up). 
  6. Put the stove down to low, and cook till the cheese melts and both sides of the bread become very crispy and is thoroughly browned. 
  7. Take the grilled cheese out of the stove, sprinkle on a tiny pinch of salt, and relish in your knowledge of the science behind the bite.