Make the Raspberry Sauce:
In a small saucepan over medium-high heat, combine raspberries, sugar, and lemon juice. Simmer while mashing the berries gently with a spoon. Once broken down, strain through a fine-mesh sieve to remove seeds. Chill the sauce in the refrigerator.

Make the White Chocolate Mousse:
In a large bowl, beat 1 ¾ cups heavy cream with powdered sugar and vanilla until stiff peaks form (about 2–3 minutes).
In a microwave-safe bowl, combine the remaining ¼ cup cream with the white chocolate chips. Microwave in 30-second bursts, stirring each time, until smooth and melted.
Gently fold the melted chocolate into the whipped cream until fully combined.

Assemble the Parfaits:
Divide half of the mousse into 6 small glasses. Add 1 tablespoon of raspberry sauce and a few fresh raspberries to each. Repeat with another layer of mousse, sauce, and berries. Optionally, sprinkle with shaved white chocolate.

Chill:
Refrigerate for at least 2 hours before serving for best texture.