4 oz bittersweet chocolate (as dark as you can find)
Sugared cranberries (optional)
Spray a deep dish 7 inch springform pan with nonstick cooking spray (could also use an 8 inch springform pan as long as it will fit inside the pot, see pot recommendations above). Line the bottom of the pan with parchment paper for easy removal of the cake once it’s done.
Stir cookie crumbs and melted butter together and press evenly across the bottom and halfway up the sides of the pan. Place in the freezer to set (this can be done 2-3 days in advance).
Cream the cream cheese with a handheld mixer on low speed until very smooth, scrape the bowl and mix again. Add sugar and cornstarch; continue to scrape and mix the ingredients together on low speed until well combined and smooth. Add eggs, one at a time, continuing to mix and scrape bowl as needed. Finally, add yogurt and vanilla and mix just until blended. Scrape the bowl and continue to stir by hand until smooth, if needed.
Divide batter into 3 separate bowls (about 2 cups each). Melt the milk chocolate in the microwave for 30 seconds, stir. Return the chocolate to the microwave for another 15-30 seconds and stir until it is completely melted and smooth. Whisk into one of the bowls of cheesecake batter. Repeat with the white and dark chocolate (each being stirred into a different bowl of batter). Refrigerate the 3 bowls for 15-20 minutes so they will be more firm for layering.
Remove the bowls from the fridge. Take the pan with the crust out of the freezer. Time to layer!
Pour dark chocolate batter into the center of the crust and smooth to form an even layer. Very carefully spoon dollops of the white chocolate batter on top of the dark chocolate, gently smooth over the top (GENTLY so the layers don’t mix together). Repeat with milk chocolate batter.
Add 1 cup of water to the pressure cooker pot and place trivet inside. Carefully lower the prepared pan onto the trivet. Secure the lid and turn pressure release knob to a sealed position. Cook at high pressure for 45 minutes.
When pressure cooking is complete, use a 10 minute natural release and then release any remaining pressure.
Remove pan from pressure cooker and let cool for 10 minutes. Slowly remove the springform ring, being careful not to break the crust. Allow the cake to cool completely and then cover and place in the refrigerator (at least 4 hours, overnight is best).
Before serving, let stand at room temperature 30-60 minutes. Decorate with sugared cranberries, if desired.