• Preheat oven to 350F degrees.
• In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar together on medium-high speed until fluffy. Alternatively, use a large mixing bowl and a handheld electric mixer.
• Beat in the eggs, one at a time. Beat in the vanilla and lemon zest. Scrape down the sides of the bowl using a rubber spatula. 
• In a large mixing bowl, whisk together the flour, baking soda and salt.
• With the mixer running on low speed, add the flour, alternating with the sour cream. Then add the bourbon.
• Coat a bundt pan generously with nonstick cooking spray. Pour the cake batter into the prepared pan.
• Bake for 1 hour and 15 minutes, until a toothpick or cake tester inserted in the center of the cake comes out clean.
• Cool on a wire rack before inverting onto a cake plate.

Make the Glaze

• In a small bowl, whisk together the powdered sugar, milk and maple syrup until smooth.
• Drizzle the glaze over the completely cooled cake.