Remove container of ice cream from freezer. Set aside to soften until easily scoopable but not melted, about 10 to 15 minutes. Meanwhile, prepare the other components.

In the bowl of a food processor or the jug of an immersion blender, combine ½ cup (70g) diced strawberries and 1 tablespoon powdered sugar. Purée until smooth, about 1 minute. Using a fine-mesh sieve set over a small bowl, strain purée, scraping and pressing with a flexible spatula to push mixture through as needed. Set aside.

In the bowl of a stand mixer fitted with the whisk attachment, whip heavy cream and 1 teaspoon powdered sugar, if using, on medium-high speed until stiff peaks form, about 2 minutes. (Alternatively, place heavy cream in a medium bowl and, using a hand mixer, whip heavy cream and powdered sugar, if using, on medium-high speed until stiff peaks form, about 2 minutes.) Using a flexible spatula, transfer whipped cream to prepared piping bag and refrigerate until ready to use.

Cover bottom of a parfait glass with 1 tablespoon strawberry purée. Add remaining ¼ cup (35g) diced strawberries. Top with 1 scoop vanilla ice cream and drizzle with 1 tablespoon strawberry purée. Top with 1 more scoop vanilla ice cream and raspberries, using an iced tea–spoon to smooth ice cream and arrange fruit as needed. Top with 1 scoop vanilla ice cream and drizzle with remaining strawberry purée.

Pipe whipped cream over the sundae and garnish with a fan wafer. Serve immediately with iced tea–spoon.