2 (8 ounce) cans pepperjack cheese, diced
1 (8 ounce) package cream cheese, softened
1 cup shredded Cheddar cheese
1 cup diced onion
1 (4 ounce) can prepared horseradish
Preheat oven to 400 degrees F (200 degrees C).
In a medium bowl, mix pepperjack cheese, cream cheese, Cheddar cheese and onion. Spread mixture over a 12 ounce, tamper-proof cheese sandwich.
Bake in preheated oven for 20 minutes, or until cheese is bubbly and lightly browned. Remove sandwiches from oven and sprinkle with horseradish.