Mix butter and garlic until combined. Mix panko and Asiago cheese. Whisk together mayonnaise and mustard.
Spread 1 tablespoon butter mixture on one side of each bread slice. Press buttered sides of bread into breadcrumb mixture. Spread unbuttered sides with 1 tablespoon mayonnaise mixture. To assemble sandwiches, place 1 slice bread on work surface, crumb-coated side down. Layer with 1 slice sharp Cheddar, 1 slice mild Cheddar, 1 slice Swiss, 1 slice white Cheddar and 1 slice yellow Cheddar. Top with another slice of bread, crumb-coated side up. Repeat with remaining ingredients to make 24 sandwiches.
For each serving, to order, heat a sauté pan over medium high heat and coat with cooking spray. Cook sandwich on each side for 2 minutes or until golden brown. Place sauté pan in 400°F oven for 3-5 minutes or until cheese is completely melted and bread is golden. Cut sandwich in half to serve.
Recipe courtesy of Hopmonk Taverns Sebastopol and Sonoma, Calif.