In a saucepan, combine 400 g frozen blueberries, 2 tablespoons lemon juice, and 2 tablespoons sugar. Cook over medium heat for 5-7 minutes, stirring occasionally, until the blueberries soften and the mixture thickens into a syrup. Remove from heat and let it cool.

Place 125 g digestive biscuits in a food processor and pulse until finely crushed. Add 42 g melted unsalted butter and pulse until the mixture resembles wet sand. Divide the biscuit mixture evenly among serving glasses or jars, pressing it down gently to form an even layer at the bottom. Place in the refrigerator while preparing the other layers.

In a heatproof bowl, melt 180 g white chocolate over a double boiler or in the microwave, stirring every 30 seconds until smooth. Let the melted chocolate cool slightly.

In a large bowl, beat 250 g low-fat cream cheese, 125 ml low-fat sour cream, and 1 teaspoon vanilla extract together until smooth and creamy.

Add the cooled melted white chocolate and mix well.

In a separate bowl, whip 125 ml whipping cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture until fully combined, creating a luscious cheesecake filling.

Spoon or pipe a layer of the cheesecake mixture over the biscuit base. Add a layer of the blueberry mixture on top. Repeat the layers as desired, ending with the blueberry layer.

Chill the parfaits in the refrigerator for at least 2 hours before serving to allow the layers to set.