Spinach Salad with Bacon, Blue Cheese, and Bourbon Vinaigrette

In a small saucepan over medium heat, bring bourbon to a boil. (If the alcohol in the bourbon ignites, quickly cover saucepan with a tight-fitting lid to tamp out the flame; then remove the lid.) Cook until liquid is reduced to about 2 tablespoons, 3 to 4 minutes. Transfer to a ramekin and refrigerate until well chilled. In a small bowl, whisk together olive oil, vinegar, syrup, salt, pepper, and reserved bourbon. Set aside. In a small skillet over medium-low heat, cook bacon until crispy, 5 to 6 minutes. Transfer to a paper-towel-lined plate. Set aside. In a large bowl, combine spinach, pecans, apple, radish, blue cheese, and reserved bacon. Toss gently with reserved vinaigrette.