To start, in a medium bowl, mix the instant coffee, sugar, and 100ml of hot water (or use 2 shots of espresso). Stir until everything is dissolved, then set aside to cool.
Next, in a large mixing bowl, pour in the double cream(heavy cream), reserving about 100ml in a separate bowl for later. Whip the remaining cream until medium-soft peaks form—light and fluffy, not stiff.
In a separate bowl, whisk together the sweetened condensed milk, mascarpone, and vanilla extract until smooth.
Add a scoop of the whipped cream into the mascarpone mixture and gently fold to loosen it. Then, add the mascarpone mixture back into the whipped cream and fold until you have a smooth, velvety ice cream base.
To make the chocolate ganache, add the reserved 100ml cream to the chocolate and microwave in 30-second bursts, stirring between each, until smooth and glossy. Set aside.
Prepare a loaf tin or dish by lining it with scrunched-up parchment paper (this will make it easier to clean later).
Pour about ⅓ of the ice cream base into the tin and smooth it into an even layer. Break the ladyfingers into medium pieces, dip them briefly into the coffee mixture, and place them over the ice cream layer. Then, drizzle over a few spoonfuls of the chocolate ganache.
Repeat these layers until everything is used, finishing with a layer of ice cream and a drizzle of ganache on top, making sure the sponge is fully covered.
Place the ice cream in the freezer for 8–12 hours, or until frozen solid.
Once frozen, dust with cocoa powder, then scoop, serve, and enjoy!