Tiramisu French Toast

0 Make the espresso custard. In a shallow bowl, whisk together the egg, cooled espresso, heavy cream, sugar, vanilla, and cinnamon until smooth.
1 Soak the bread. Add the sourdough slices to the custard and soak for 1 to 2 minutes per side, depending on the thickness of the bread. The slices should be well saturated but still sturdy.
2 Cook the French toast. Heat a skillet over medium heat and add butter. Cook the soaked sourdough until golden brown on the first side, then flip and cook until golden on the second side and warmed through in the center.
3 Make the mascarpone cream. Whip the heavy cream until it begins to thicken. Add the mascarpone, powdered sugar, and vanilla bean paste, then continue whipping until fluffy and pipeable. Be careful not to overwhip.
4 Assemble. Transfer the warm French toast to a serving plate. Pipe or spoon the mascarpone cream generously over the top.
5 Finish and serve. Dust generously with unsweetened cocoa powder and serve immediately, with fresh berries if desired.