Place 4 tortillas on a flat surface. Spread an even layer of refried beans onto each side facing up.
Heat a large skillet over medium-high heat. Add 2 tablespoons of butter and melt. Add red pepper and red onion, saute until soft, about 5 minutes. Add the corn, red pepper flakes, cumin, salt, and pepper. Stir and saute for about 3 minutes longer. Transfer to a bowl and stir in cilantro.
Turn heat down to medium. Add 1 tablespoon of butter to skillet. Add one tortilla to skillet, bean side up. Sprinkle half of the corn mixture into an even layer over top the beans. Sprinkle half of the cheese on top in an even layer.
Cover with a prepped tortilla, bean side down. Cook until cheese starts to melt. Flip to toast the other side, about 3 minutes. Remove from skillet. Repeat the process with the remaining prepped tortillas. Cut finished quesadillas into wedges.
Cilantro Lime Sour Cream
In a small bowl, mix the sour cream, cilantro, lime juice, and salt. Serve with finished quesadillas and enjoy!