Step 1

Preheat oven to 350 degrees Fahrenheit.

Step 2

Cut the mushroom in half. Warm an 8-inch, ovenproof skillet over medium heat, then add just enough oil to coat its surface. Add mushroom, flat side down, and drizzle it with 1 teaspoon oil, then season with salt.

Step 3

Move skillet to oven and cook for 3 minutes.

Step 4

Meanwhile, heat a second, cast-iron skillet on medium just until the pan starts to smoke. Add Oaxaca cheese evenly, and do not touch.

Step 5

Turn heat down to medium low. When you notice cheese browning at the edges, remove skillet from heat and place in the oven.

Step 6

Let the cheese melt completely, then remove skillet from oven.

Step 7

Remove the other skillet from the oven. Flip over the mushroom, then add butter and garlic to the still-hot skillet around the mushroom. When butter has melted and garlic is fragrant, transfer the mushroom, garlic, and butter to center of cheese.

Step 8

Season with salt and chives. Serve immediately, while cheese is still bubbling, with hot flour tortillas.