Preheat the oven to 350°F (175°C). Spread about 1 cup of salsa evenly over the bottom of a 9×13-inch baking dish.
Bring a large pot of salted water to a rolling boil. Add the jumbo shells and cook 8–9 minutes, just under al dente so they are flexible but not floppy. Drain in a colander and let cool enough to handle.
Heat 1/2 teaspoon olive oil in a large skillet over medium-high heat. Add 1 teaspoon minced garlic and cook 1–2 minutes until fragrant.
Add 1 pound ground beef to the skillet, break it up with a spatula, and season with 1/2 teaspoon salt. Cook until no longer pink, then drain any excess grease.
Stir in 1 cup corn, 2 tablespoons taco seasoning, and 1/4 cup of the salsa. Cook until heated through and the seasoning is dissolved.
Mix 1/2 cup of shredded cheddar into the meat until just melted. Remove the skillet from the heat.
Spoon the meat mixture into each cooked shell (divide evenly), and arrange the stuffed shells in the prepared baking dish on top of the salsa in rows.
Place dollops of the remaining salsa over each shell, then sprinkle the rest of the shredded cheddar evenly on top. Cover the dish with aluminum foil.
Bake covered for 20–25 minutes, until heated through and the cheese is melted and gooey. Remove foil and serve.
