Prepare the Crust:

1. Preheat oven to 350°F (175°C). Grease an 8-inch springform pan and line the bottom with parchment paper.
2. Process cookies in a food processor until finely ground. Mix with melted butter until combined.
3. Press the mixture into the bottom and about 1 inch up the sides of the pan.
4. Bake for 10-12 minutes until firm and fragrant. Let cool slightly.

Prepare the Filling:

1. Lower oven temperature to 300°F (150°C).
2. Beat the cream cheese on medium-low speed until creamy (about 2 minutes).
3. Add sour cream and mix until smooth, scraping down the sides of the bowl as needed.
4. Mix in sugar, espresso powder, vanilla extract, and salt until combined.
5. Add eggs one at a time, beating just until combined after each addition.
6. Gently stir in Baileys Irish Cream.

Bake the Cheesecake:

1. Pour filling over the cooled crust.
2. Place the springform pan inside a larger roasting pan. Fill the roasting pan with hot water until it reaches halfway up the sides of the springform pan.
3. Bake for 1 hour 5 minutes, until the center is set with a slight jiggle.
4. Remove from oven and let cool in the water bath for 15 minutes.
5. Transfer cheesecake to a wire rack and cool completely before refrigerating for at least 4 hours or overnight.

Prepare the Ganache:

1. In a small saucepan, heat heavy cream, Baileys Irish Cream, and espresso powder over medium heat until just simmering.
2. Pour over milk chocolate chips in a heatproof bowl and let sit for 2 minutes.
3. Stir until smooth. Let cool slightly, then pour over the chilled cheesecake, spreading evenly.
4. Refrigerate for at least 30 minutes to set.

Serve:

• Remove cheesecake from the springform pan.
• Slice and serve with sweetened whipped cream if desired.