Maple Bourbon Burger with Bacon Mustard Sauce

Bahan-bahan (4 porsi)

• 4 slices bacon
• ¼ cup spicy brown mustard
• ¼ cup honey
• 1 teaspoon horseradish
• 1 pound lean ground beef
• ¼ teaspoon kosher salt
• ¼ teaspoon freshly ground black pepper
• ½ cup maple syrup
• 3 tablespoons bourbon
• 4 slices smoked gouda
• 4 large hamburger rolls
• 4 leaves lettuce
• 4 slices tomato
• 4 slices onion