Heat oven to 350°F (176ºC) with rack set in middle position. Coat an 8½ × 4½-inch loaf pan with nonstick spray. Line pan with parchment paper, leaving a 2-inch overhang on two sides; coat paper with nonstick spray.
Whisk together flour, baking powder, cinnamon, ginger, baking soda, and salt in a large bowl, set aside.
Whisk together milk, eggs, maple syrup, oil, butter, bourbon (if using), and vanilla until smooth. Stir in dates and let sit 10 minutes. Fold flour mixture into milk mixture with a rubber spatula until combined. Fold in nuts.
Scrape batter into prepared pan and smooth top. Sprinkle turbinado sugar evenly over top.
Bake until golden brown and a toothpick inserted in the center of loaf comes out with few moist crumbs attached, 55–60 minutes. (All ovens vary in temperature so start checking bread at 45 minutes.)
Let bread cool in pan on wire rack for 10 minutes, then turn bread out onto wire rack to cool completely, at least 1 ½ hours.
Store bread wrapped in parchment paper (I just use the paper from baking) and foil, or in a zipper-lock bag at room temperature for up to 3 days, though it’s best within 2 days. If you need to store it longer, pop it in the refrigerator for up to 5 days.