Oreo Tiramisu

1 . Stage

In a large heatproof bowl set over a pot of simmering water, whisk egg yolks and granulated sugar until doubled in volume and velvety smooth, about 4 minutes. Remove from heat and let cool slightly.  

2 . Stage

In another large bowl, beat heavy cream, powdered sugar, vanilla, and ¼ teaspoon salt, just until stiff peaks form, about 5 minutes.  

3 . Stage

Whisk mascarpone into slightly cooled egg mixture, then gently fold in whipped cream. 

4 . Stage

In a measuring cup or other tall glass, combine boiling water and coffee, then stir in rum. Dip Oreos in coffee, one at a time. 

5 . Stage

Line the bottom of a 8"-x-8" baking dish with 16 dipped Oreos. Pour half the custard over top and smooth with a spatula. Repeat with remaining dipped Oreos and custard. Cover and refrigerate for 4 hours and up to overnight. 

6 . Stage

When ready to serve, dust top of tiramisu with cocoa powder.