Cook the raspberry mixture

• Add the raspberries and granulated sugar to a saucepan over medium-high heat.
• Cook, stirring regularly, until the fruit breaks down.

Strain the raspberry mixture

• Place a sieve over a bowl and pour in the raspberry mixture.
• Press firmly with a spatula or spoon to strain out the seeds.
• Reserve a portion of the raspberry mixture and put the rest in a piping bag.

Make the white chocolate ganache

• Heat the heavy cream almost to a boil.
• Add the chopped white chocolate and let it sit for 1 minute.
• Mix until smooth.

Flavor the ganache

• Put the white chocolate ganache in a deep bowl and add a portion of the raspberry mixture.
• Mix everything well together until smooth.

Make the cookie dough

• Melt the butter over low heat in a saucepan.
• Put the tea biscuits and powdered sugar in a food processor and grind them finely.
• Put the finely ground tea biscuits in a deep bowl, add the melted butter and mix together.

Melt the white chocolate

• Melt the remaining white chocolate using a double boiler.

Assemble the layers

• Spread the cookie dough evenly over the bottom of a dish or baking pan and press it firmly using the bottom of a spoon.
• Add the raspberry mixture and spread it evenly over the cookie dough.
• Add the melted white chocolate and spread it evenly.

Decorate and chill

• Drizzle the raspberry mixture on top and use a toothpick to create a decorative pattern.
• Place the cake, covered, in the refrigerator to set, preferably overnight.

Cut and serve

• Cut the cake into pieces the next day.