Melt 1/2 cup of butter in a saucepan over medium heat. Add the onion; cook and stir until deep brown, about 15 minutes. Stir in the maple syrup and trail mix. Heat to 300 to 310 degrees F (149 to 154 degrees C), or until a small amount of syrup drizzled from a spoon forms hard, brittle threads. Pour onto parchment paper, and allow to cool.
Preheat the oven's broiler.
In a small bowl, stir together the remaining butter and garlic. Spread onto the cut side of the focaccia bread halves. Crumble the candied trail mix and onion over the garlic butter, and top with Romano cheese. Place the focaccia onto a baking sheet.
Broil for 3 to 5 minutes, or until golden brown. Cut into wedges to serve.
