Whisk together 3/4 cup sugar and 3 eggs until thick. In a medium saucepan, bring the milk to a simmer. Whisk a few tablespoons warm milk into the egg mixture, then pour the mixture into the pan. Cook over low heat, stirring constantly, until the mixture coats a spoon, about 6 minutes. Remove from the heat and whisk in the creamy peanut butter. Strain into a bowl. Stir in 1 1/2 cups cream, the peanuts, vanilla and salt and refrigerate for 2 hours.
Scrape the chilled peanut butter mixture into an ice cream maker and prepare according to the manufacturer's directions.
Preheat the oven to 350 degrees . Line 2 baking sheets with parchment paper. Using an electric mixer, combine the crunchy peanut butter, the remaining 1 cup sugar and 1/4 cup chocolate chips on medium speed. Whisk together the remaining egg and the baking soda, then mix into the crunchy peanut butter mixture until combined. Place tablespoon-size balls of dough 2 inches apart on the baking sheets. Bake until golden, about 16 minutes. Let cool on the baking sheets.
In a small saucepan, bring the remaining 1/2 cup cream to a boil. Remove from the heat and stir in the remaining 1/2 cup chocolate chips until smooth. Cover to keep warm.
Assemble the ice cream sandwiches and drizzle with the chocolate sauce before serving.