Preheat oven to 375 degrees. Grease a 9x13 casserole dish and set aside.

Pat the shrimp dry with paper towels and roughly chop.

In a skillet over medium heat, melt the butter. Add the garlic, onion, and jalapeño and saute 1 to 2 minutes.

Add the shrimp and saute until the color begins to slightly turn. You want to leave them undercooked because they will finish in the oven. Use a slotted spoon to transfer the shrimp mixture to a medium sized bowl and set aside.

Rinse the skillet and return to the stovetop. Set the heat to medium low and add the salsa, broth, and sour cream. Stir continuously while the sauce heats up. Add 1.5 cups of the monterey jack cheese and stir until silky smooth. Do not overcook the sauce. Remove from heat.

Add about 2 or 3 tablespoons of the sauce mixture to the shrimp mixture. Wrap each tortilla with the shrimp mixture, roughly 2 tablespoons per tortilla. Lay the enchiladas seem side down in the casserole dish.

Pour the cheese sauce over the top of the enchiladas. Top with remaining 1/2 cup of monterey jack.

Bake for 20 to 25 minutes until the cheese is melted and bubbly. Let rest 5 to 10 minutes before serving.