01 -
Line an 8x8-inch baking pan with parchment paper, leaving overhang on two sides. Lightly grease the parchment if your pan tends to stick.
02 -
Add white chocolate chips and butter to a heavy saucepan over low heat. Stir until mostly melted, remove from the heat, then stir until smooth.
03 -
Stir in the dulce de leche and fine salt until smooth. Fold in the marshmallow cream, then spread the mixture evenly in the prepared pan.
04 -
Refrigerate the caramel layer for about 30 minutes, until the surface is set enough to hold the next layer without mixing.
05 -
Stir the instant espresso powder with the hot water until dissolved. Mix it into the sweetened condensed milk until evenly blended.
06 -
In a clean saucepan over low heat, melt the white chocolate chips with butter. Stir in the coffee condensed milk, then fold in the marshmallow cream until glossy.
07 -
Spread the coffee layer gently over the caramel layer. Refrigerate for at least 4 hours, or overnight, until fully firm.
08 -
Lift the fudge out of the pan and cut into small squares with a warm dry knife. Melt the dark chocolate wafers, drizzle over the squares, and sprinkle with flaky salt if using.