Preheat oven to 425 degrees F (220 degrees C). Grease a 9-inch baking dish with cooking spray.
Beat eggs in a large bowl with a fork until slightly frothy. Mix in sour cream and Mexican seasoning. Add salsa, tomato, onion, and cilantro. Pour into the prepared baking dish. Sprinkle 3/4 cup Mexican cheese blend on top; stir in gently with a fork.
Bake in the preheated oven until firm and springs back when gently pressed, about 20 minutes. Sprinkle remaining 3/4 cup Mexican cheese blend and jalapeno on top. Continue baking until cheese bubbles and turns golden, 5 to 10 minutes.
Let frittata stand for 10 minutes before slicing with a serrated knife.