Special equipment: an ice cream maker
For the ice cream: In a medium saucepan set over medium-low heat, combine the cream, 1/2 cup of the granulated sugar and the vanilla seeds. Bring the mixture just to a simmer, stirring occasionally. Remove from the heat, then add the white chocolate and whisk until combined and smooth.
In a small bowl, combine the eggs and the remaining 1/2 cup granulated sugar, and beat until smooth.
Strain the cream mixture through a fine mesh sieve, and then whisk a third of the cream mixture into the eggs. Immediately whisk the eggs into the remaining cream mixture. Chill the ice cream base over an ice bath and freeze for 30 minutes.
Using an ice cream maker, churn the ice cream base according to the manufacturer's instructions. Freeze in an airtight container for 1 hour.
For the cookies: Preheat the oven to 350 degrees F. Line two cookie sheets with parchment paper. Sift the flour, baking soda and salt into a medium bowl and set aside.
In the bowl of a stand mixer fitted with the paddle attachment on medium speed, cream together the butter, brown sugar and granulated sugar until light and fluffy. Scrape down the sides of the bowl with a rubber spatula. Beat in the vanilla and eggs. Gradually add the dry ingredients to the mixer, and mix until the batter is smooth. Turn off the mixer and fold in half of the pistachios and the lemon zest using the spatula.
Scoop about 1/4 cup of the cookie dough at a time onto the prepared cookie sheets, leaving some room between each cookie, for about 12 cookies total. Press down the tops of the dough slightly and sprinkle with some nonpareils. Bake until the cookies are light brown, 12 minutes for chewy cookies or about 15 minutes for crispy cookies.
Cool the cookies on the baking sheets for 5 minutes and then transfer to a wire rack to cool completely.
In a shallow dish, combine the remaining pistachios with the blueberries. Using an ice cream scoop, scoop some ice cream onto a cookie, and top with another cookie to form a sandwich. Repeat for the remaining cookies and ice cream. Roll the edges of the ice cream sandwiches in the pistachio-blueberry mixture and freeze for 10 minutes before serving.