Gently rinse squash blossoms and pat dry. Remove the stamens and any tough stems. Roughly chop the blossoms.
Lay 4 tortillas on a work surface. Divide the cheese evenly among them, leaving a border. Top with squash blossoms, epazote, and a pinch of salt. Add jalapeño slices if using.
Place the remaining 4 tortillas on top to form quesadillas.
Heat a large skillet or comal over medium heat and lightly brush with oil. Cook each quesadilla for 2-3 minutes per side, until golden brown and cheese is melted.
Cut into wedges and serve immediately with salsa and crema.
Tips
Use fresh squash blossoms for best flavor; they are available at farmers markets or Latin grocery stores.
Oaxaca cheese is ideal for its stringy texture, but mozzarella or Monterey Jack work well.
To keep warm, place cooked quesadillas on a baking sheet in a 200°F oven.