Combine the cream cheese, marshmallow fluff, Nutella, cold coffee, and heavy cream until smooth and fluffy.
Spread some of the s'mores cream over half of the chocolate graham crackers and top each one with banana slices and a plain chocolate graham cracker.
Spread some Nutella over half of the regular graham crackers and top each one with strawberry slices and a plain regular graham cracker.
Grease the ring of a springform pan, place it on a serving platter without the springform pan base, and arrange the strawberry and banana s'mores upright in a circle inside the springform ring.
Brush the cold coffee with milk over the strawberry and banana s'mores to soften them.
Pour the remaining s'mores cream over the s'mores and smooth out the top. Refrigerate the strawberry banana s'mores cake for 4 hours.
Carefully remove the springform pan ring and garnish the cake with cocoa powder, powdered sugar, mixed berries, and fresh mint leaves before serving.