Chocolatey Oreo crust, creamy whipped Baileys' filling and chocolate ganache drizzle for a decadent and show stopping dessert.
Preheat oven to 350° F. Melt butter in microwave in short bursts (30 seconds to start, then in 20 second intervals until melted). Mix with crushed Oreos and press firmly into a fluted tart pan (I use a rectangular 4.5" (11.5 cm) x 13" (34 cm) x 1" (3 cm) fluted tart pan).
Bake for 5-10 minutes. Remove from oven and let fully cool in pan. Chill in fridge until cold.
Whip mascarpone and sugar with an electric mixer for 2-3 minutes until stiff peaks form. Add Baileys and whip until just blended. Fill Oreo crust with filling. Return to fridge and chill.
Place chocolate chips and Baileys (or whipping cream) in a small bowl and heat in short bursts until melted (start with 30 seconds and then 20 second intervals until mostly melted. Some small lumps will melt upon stirring). Stir together and allow to cool for 3-4 minutes. Stir again and drizzle over chilled tart. Return to fridge and chill for 20-30 minutes more before serving.