Step 1

Heat oil and butter over medium heat in a large pan. Add onions and salt, cook, stirring occasionally for 20-25 minutes or until onions are a deep brown. Add red wine, in splashes (about 3 additions), to onions. Stirring and allowing all liquid to absorb before adding more. Remove from heat and set aside.

Step 2

Heat a grill pan or regular pan over medium heat. Butter both pieces and sides of bread. Spread one slice with horseradish. Top a quarter of the cheese, top with one rounded tbsp of caramelized onions. Add half the apple slices, top with more cheese and slice of bread.

Step 3

Cook on stovetop for about 5 minutes, turning the heat down to avoid burning. Flip and cook until golden brown on the other side another 3-5 minutes.

Step 4

Repeat with remaining ingredients for second sandwich.