Place eggs, espresso, cream, cocoa powder, cinnamon and vanilla extract in a large bowl. Whisk to combine.
Dip one bread slice in egg mixture, turning to coat both sides evenly. Soak 3 minutes.
Meanwhile, heat butter in a large frying pan over medium heat.
Fry bread slice until golden brown, 2 to 3 minutes per side.
Repeat with the remaining bread slices and butter. Set aside.
Combine together mascarpone and honey. Set aside.
Spread one side of half of the bread slices with mascarpone mixture. Top with another bread slice.
Dust with cocoa powder. Decorate with berries.
Serve with chocolate sauce.