Line an 8x8-inch (20cm) square tin with baking paper and set aside.
Place the Jammie Dodger biscuits in a food processor or high-powered blender and blitz until fine crumbs form. Transfer the crumbs to a large mixing bowl, then add the melted butter and 90g of the condensed milk (keep the rest for later).
Stir until the mixture resembles a wet dough. Press it firmly and evenly into the base of your prepared tin. Set this aside for now.
Break the white chocolate into small pieces and place them in a heatproof bowl with 300g of condensed milk (The rest of the tin we used earlier). Melt together in the microwave, heating in 15–30 second bursts and stirring between each until smooth and glossy.
Working quickly, pour the melted chocolate mixture over the biscuit base and spread it out evenly with a spoon or palette knife. Swirl through some raspberry jam.
Arrange 9 mini jammie dodgers on top, either whole or lightly crushed for texture.
Refrigerate for at least 3 hours, or until the topping is firm to the touch. Once set, lift out of the tin, cut into slices, and enjoy your creamy, crunchy no-bake treat!
