Chocolate Cookie Crust

1. Preheat oven to 325F. Line an 8” x 8” square baking pan with parchment paper in a crisscross fashion so that all sides of the pan are lined with parchment paper. Set aside.
2. Add chocolate cookie crumbs into a medium mixing bowl, pour in melted butter and mix until mixture resembles wet sand.
3. Transfer chocolate cookie crust mixture to prepared pan. With the back of a measuring cup, gently press crust mixture into an even layer.
4. Bake chocolate cookie crust for 12 minutes.
5. Cool chocolate cookie crust to room temperature while cheesecake batter is being prepared.

Irish Cream Cheesecake  

1. Reduce oven temperature to 300F.
2. In the bowl of a stand mixer fitted with a paddle attachment, add in the cream cheese, sugar, and cornstarch and beat at medium speed (4 on stand mixer) for 5 minutes. Stop mixer and with a flexible spatula, scrape the sides and base of bowl.
3. Add yogurt and vanilla extract into the cream cheese mixture and mix a low speed (2 on stand mixer) until incorporated (about 30 seconds).
4. Slowly pour in the Irish cream liquor and allow liquor to mix into batter (about 30 seconds).
5. With the mixer running at low speed, mix in the egg yolks one at time allowing each yolk to be incorporated into Irish cream cheesecake batter before adding the next one.
6. Once all the egg yolks have been mixed into batter turn off mixer and give batter a good mix with a flexible spatula taking care to scrape the sides and bottom of bowl.
7. In a separate medium mixing bowl, add eggs whites. With a whisk or hand-held mixer, whisk egg whites at high speed until it reaches medium stiff peaks. If you were to hold the whisk/beaters upright, the peak should fold over and not be stiff.
8. Use a spatula to fold half of the whipped egg whites into Irish cream cheesecake batter making sure to reach the bottom of the bowl. Repeat with the second half of whipped egg whites. Take care to lightly fold whipped egg whites into cheesecake batter to avoid deflating the air out of egg whites.
9. Pour Irish cream cheesecake batter over cooled chocolate cookie crust. Use an offset spatula to spread batter into an even layer. 
10. Bake Irish cream cheesecake for 40 minutes. Cheesecake is ready once the edges appears firm, slightly puffed and the center has a slight giggle.
11. Cool Irish cream cheesecake to room temperature for at least (1) hour.
12. Once cheesecake has cooled to room temperature, refrigerate for at least 4 hours or overnight.

Chocolate Ganache Glaze

1. Finely chopped chocolate and add into a medium mixing bowl.
2. Heat up heavy cream and Irish cream liquor just until hot but not boiling either on stovetop or in the microwave at 30 second intervals.
3. Pour warmed heavy cream and Irish cream liquor over the top of chopped chocolate.
4. Allow mixture to sit untouched for at least 30 seconds.
5. Whisk heavy cream and liquor into chopped chocolate starting inward and moving outward until all the chocolate is melted. Chocolate ganache should be smooth and shiny without any lumps of chocolate.

Chocolate Whipped Cream Frosting

1. Place a medium mixing bowl in the freezer to chill for at least 10 minutes.
2. Add heavy cream, Irish cream liquor (optional), powdered sugar, cocoa powder and vanilla extract into chilled mixing bowl.
3. With a whisk or hand-held mixer, whip cream mixture together until stiff peaks form.
4. Transfer chocolate whipped cream frosting to a pastry bag fitted with your favorite pastry tip. I used this tip.

Assembly

1. Remove Irish cream cheesecake from pan.
2. Use a sharp knife to cut Irish cream cheesecake into 16 equal bars/squares.
3. Place a cooling rack over a sheet of parchment paper and transfer cheesecake bars to cooling rack.
4. Pour cooled but pourable chocolate ganache glaze over each of the Irish cream cheesecake bars.
5. Pipe chocolate whipped cream frosting on top of each bar.
6. Decorate with chocolate shavings (optional).