Preheat oven to 350 degrees F (175 degrees C) and grease a 9-inch springform pan.

Combine graham cracker crumbs, oats, and brown sugar in a food processor until oats are roughly cut.

Add melted butter and vanilla extract; pulse until evenly textured.

Press mixture into the bottom of the prepared pan.

Bake crust for 7 minutes and allow to cool.

Reduce oven temperature to 325 degrees F (160 degrees C).

Heat whipping cream just below a simmer.

Pour hot cream over chopped chocolate; whisk until smooth and set aside to cool slightly.

Beat cream cheese in a bowl until fluffy, scraping the sides.

Gradually add granulated sugar while beating, scraping the bowl.

Beat in cornstarch.

Slowly pour in Irish cream and beat in the eggs, one at a time.

Pour the chocolate mixture into the cheesecake filling and blend well.

Scrape filling into the prepared pan.

Bake for 30 minutes.

Turn off the oven and leave cheesecake inside for another 30 minutes without opening the door.

Remove the cheesecake and let it cool to room temperature.

Chill in the refrigerator overnight before serving.