Prep the shrimp: Pat shrimp dry with paper towels. Dry shrimp sear better and won’t steam.
Season: In a bowl, toss shrimp with 1 tablespoon olive oil, garlic, chili powder, smoked paprika, cayenne, cumin, salt, black pepper, and lime juice.
Let sit for 5 minutes while you heat the pan.
Cook the shrimp: Heat a large skillet over medium-high. Add remaining 1 tablespoon olive oil. Cook shrimp in a single layer for 1–2 minutes per side until pink and just opaque.
Transfer to a plate; roughly chop into bite-size pieces. Stir in cilantro if using.
Assemble quesadillas: Wipe the skillet lightly if needed. Reduce heat to medium.
Add a small knob of butter or a drizzle of oil. Place one tortilla in the skillet.
Layer the fillings: Sprinkle a mix of Monterey Jack and cheddar over half the tortilla. Add a generous layer of shrimp.
Top with a little more cheese. Fold the tortilla over to close.
Cook until crispy: Press gently with a spatula. Cook 2–3 minutes per side until golden and the cheese melts.
Adjust heat to avoid burning.
Repeat: Transfer to a cutting board. Cook remaining tortillas the same way.
Serve: Cut into wedges. Finish with extra lime, hot sauce, or a dollop of sour cream.