In a large skillet, cook the ground beef, onion, and garlic over medium heat until the beef is no longer pink. Drain any excess grease.
Add cumin, garlic salt, Cajun seasoning, pepper, oregano, crushed red pepper flakes, and chili powder to the beef mixture.
Stir in tomato sauce and diced jalapeños. Simmer for 15 minutes to meld flavors.
Preheat the oven to 425°F (220°C). Lightly flour a surface, then unroll the pie crusts.
Use a 4-inch bowl as a cutter to make circles. Each crust yields about 4 circles.
Moisten the edges of each dough circle with water.
Place a bit of grated cheddar and Monterey Jack cheese in the center, then top with about ¼ cup of the beef mixture.
Fold the dough over into a half-moon shape and press the edges with a fork to seal. Place on a baking sheet.
In a small bowl, whisk the egg with 1 Tbsp water. Brush the tops of each empanada with this egg wash for a golden finish.
Bake the empanadas for 15 minutes, or until the crust turns golden brown.