Preheat oven to 350 degrees. Grease and lightly flour a ten inch bundt pan.
In a medium bowl, whisk together flour, baking powder, soda, salt, cinnamon, ginger, and nutmeg.
In the bowl of an electric mixer, beat butter on medium high speed until light and fluffy. Reduce speed to low and gradually add sugar. Beat on medium high speed until mixture is light colored and fluffy, about 3 minutes.
Add eggs one at a time, beating after each addition. Beat in vanilla bourbon syrup.
At low speed, add 1/3 of the flour mixture followed by half of the sour cream. Repeat, ending on the flour mixture. Beat on medium low speed until well combined.
Spoon half of mixture into bundt pan, spreading evenly. Layer with fresh diced pears. Spoon the remaining batter over top of the pears.
Bake for 50-60 minutes or until toothpick inserted in center of cake comes out clean. Cool for about 10 minutes. Set a wire rack over a baking sheet. Invert cake onto cooling rack.
Meanwhile, make the glaze. Place the butter in a small sauce pan over medium heat. Cook, stirring occasionally, until butter begins to foam and turns a toasty brown color. Pour the butter into a mixing bowl, leaving most of the brown sediment on the bottom of the pan behind. Whisk in the powdered sugar and 2 Tablespoons milk, vanilla syrup, and salt. Add additional milk if needed until the consistency is thick but pourable.
Once the cake has mostly cooled, pour the glaze on top, allowing it to drip down the sides. Serve at room temperature or (my favorite) warmed with milk or ice cream.