Melt butter in a skillet over medium heat; stir in onion, garlic, jalapeño pepper, and epazote and cook until soft, about 5 minutes.

Stir corn truffles into onion mixture; cook and stir until truffle liquid has evaporated, about 10 minutes. Season with salt and keep warm.

Heat a large griddle or skillet over medium heat until hot. Moisten both sides of two tortillas with water and place them, stacked together, onto the hot griddle; cook until bottom tortilla is crisp, about 2 minutes. Flip stacked tortillas and cook other tortilla until crisp, about 2 minutes.

Separate two tortillas; place them separately, uncooked-side down, onto the hot griddle. Cover crisp side of one tortilla with 1/5 of the Oaxaca cheese; place 1/5 of corn truffle mixture over cheese, then lay crisp side of second tortilla on top to cover truffle mix.

Cook, turning once, until both tortillas are crisp and cheese is melted, about 3 minutes; repeat with remaining tortillas, cheese, and corn truffle mixture.