Heat oven to 350 °F.
Add pretzels, 1/4 cup peanuts and brown sugar to bowl of food processor fitted with steel blade. Pulse until mixture resembles very coarse sand with few larger pieces remaining. Pulse in butter until well combined.
Press about 3/4 cup of mixture into bottom of 9" springform pan. Spread remaining mixture in even layer on rimmed baking sheet. Bake crust and crumbs until light golden and fragrant, about 4 to 5 minutes. crust may take bit longer to brown (another 2 to 3 minutes).
Set pans on rack to cool completely.
When crust and crumbs are cool, transfer 1 quart of ice cream to large bowl and use wooden spoon to break it into few pieces.
Let ice cream sit at room temperature until slightly softened, about 10 minutes.
Drizzle half peanut butter over top and gently fold it into ice cream, so some ribbons of peanut butter remain.
Scoop ice cream mixture onto cooled crust and use offset spatula to gently spread it to edges of pan, being careful not to pull crust away from bottom of pan.
Drizzle top of ice cream with 1 Tbsp of honey and use tip of knife or wooden skewer to swirl it as best you can into surface of ice cream.
Sprinkle about 1/2 cup of peanut-pretzel crumbs from baking sheet over top and gently press them into ice cream.
Cover pan with plastic wrap and place cake in freezer.
After about one hour, soften second quart of ice cream, and mix remaining half of peanut butter into it, and spread as before.
Drizzle remaining honey over top and swirl it into surface of ice cream. Cover pan with plastic wrap and return it to freezer to chill cake for at least 4 hours before serving, and up to overnight.
Just before serving, whip heavy cream to soft peaks, and stir remaining whole peanuts into remaining peanut-pretzel crumbs.
To un-mold cake, run thin knife or offset spatula under hot water to warm it, and slide it around edges of cake. Remove outer ring of springform pan, dollop top of cake with whipped cream, lightly spread it to edge, and sprinkle remaining peanut-pretzel mixture around top edge.
Slice and serve.