Step 1

Time to do a little knifework: Peel and finely chop 1 small onion. Peel 3 garlic cloves. Finely chop ⅓ cup pickled jalapeños.

Step 2

Using a box grater, coarsely grate 8 oz. American cheese (or tear if using singles) and 8 oz. Monterey Jack cheese (you should have about 4 packed cups). Set aside separately.

Step 3

Heat 2 Tbsp. unsalted butter in a medium saucepan over medium until foamy, about 1 minute. Reduce heat to medium-low and add onions. Using a Microplane, finely grate garlic into pot; season with 1 tsp. salt. Cook, stirring occasionally, until onions are tender but haven’t developed any color, about 3 minutes. Add 2 tsp. ground cumin and ½ tsp. cayenne pepper and cook, stirring frequently, until aromatic, about 30 seconds. Stir in 1¾ cups milk and bring to a bare simmer.

Step 4

Meanwhile, whisk 1 Tbsp. cornstarch and remaining ¼ cup milk in a small bowl until smooth. By mixing the cornstarch with a portion of the milk before adding it into the pot, you greatly reduce your chance of lumps. (You can also shake milk and cornstarch together in small lidded jar.)

Step 5

Add cornstarch mixture to pot and bring to a simmer over medium heat. Cook, stirring constantly, until mixture is thickened (it should coat the back of your spatula) and cornstarch is hydrated—it should simmer for 1 full minute. This is important: If your cornstarch isn't fully hydrated, your queso will be grainy and floury rather than thick and creamy.

Step 6

Reduce heat to medium-low and add American cheese. Stir vigorously with a spatula, taking care not to let mixture bubble, until cheese is fully melted, about 3 minutes.

Step 7

Add Monterey Jack cheese one handful at a time, stirring vigorously to incorporate fully before adding the next and adjusting heat as needed so mixture doesn't bubble, about 30 seconds between additions and 4 minutes total. After adding all the cheese, stir vigorously to ensure that all cheese is melted, about 1 minute (it will look thick and stringy).

Step 8

Remove from heat and stir in 1 Tbsp. pickling liquid and half of jalapeños. Taste and add more salt if needed. Garnish with remaining jalapeños.

Step 9

Arrange chips on a platter or baking sheet. Serve queso right out of the pot so it stays warm and can be easily reheated over medium-low heat if needed. If you’re feeling real extra, set pot over another pot or large bowl filled with hot water so it stays gooey for longer.