Make the broccoli filling. Steam the broccoli crown for four minutes, then remove from the heat. Rinse with cold water and pat dry. Slice 1/4 inch thick. Heat the oil over medium-high heat in a large, heavy frying pan, and add the red onion. Cook, stirring, until tender and seared on the edges. Add the sliced broccoli. Cook, stirring, until seared on the edges, about three minutes. Stir in the cilantro or epazote, season with salt and pepper, and remove from the heat. Taste and adjust seasoning.
In a microwave: Place a corn tortilla on a plate. Top with half the broccoli and onions, and spread in an even layer. Sprinkle on half the cheese, and top with another tortilla. Press down gently, then microwave for 1 to 1 1/2 minutes until the cheese has melted. Remove from the microwave, cut into quarters or sixths, and serve. Repeat with the remaining ingredients.
In a pan: Place a corn tortilla in a pan. Top with half the broccoli and onions, and spread in an even layer. Sprinkle on half the cheese. Turn the heat on medium-high, and heat until the cheese begins to melt and the tortilla begins to brown. Place another tortilla on top of the cheese, and press down lightly. Flip over the quesadilla in the pan, and heat for about 30 seconds or until the cheese has melted. Flip back over, and remove to a plate. Cut into quarters or sixths, and serve. Repeat with the remaining ingredients.