Preheat oven to 375 degrees F (190 degrees C). Lightly grease a 9x13-inch baking dish.
Heat a large skillet over medium-high heat. Cook and stir beef with black pepper, salt, and garlic powder in the hot skillet until meat is browned and crumbly, 5 to 7 minutes; drain and discard grease. Reduce heat to low and mix 1/2 cup ketchup into beef.
Lay a tortilla onto a work surface and place about 1/3 cup beef mixture and 1/4 cup shredded cheese onto tortilla in a line down the center. Roll tortilla over meat and cheese, fold in top and bottom to enclose filling, and finish rolling into a burrito shape. Repeat with remaining tortillas and filling. Place filled tortillas into prepared baking sheet and sprinkle remaining Mexican cheese blend on top. Cover dish with aluminum foil.
Bake in the preheated oven until dish is heated through and cheese topping has melted, 20 to 25 minutes. Stir sour cream with 1/3 cup ketchup in a bowl and top each serving with the sour cream sauce.
