Prepare the pan. Center a rack in the oven and preheat the oven to 350F. Butter a 9-inch springform pan and place it on a baking sheet lined with parchment or a silicone mat.
Prepare the peanut mixture. Toss ½ cup of the chopped peanuts, 2 tsp sugar, ½ tsp espresso powder, ¼ tsp cinnamon, a pinch of nutmeg, and ½ cup chocolate chips together in a small bowl. Set aside.
Make the Oreo crust. Put the Oreo crumbs, 4 Tbsp melted butter, and pinch of Kosher salt in another small bowl and stir with a fork just until the crumbs are moistened. Press the crumbs evenly over the bottom and up the sides of the springform pan (they should go up about 2 inches on the sides). Freeze the crust for 10 minutes.
Bake the crust. Place in an oven, then bak for 10 minutes. Transfer to a wire rack and let it cool completely before filling.
Make whipped cream. Working with a stand mixer fitted with the whisk attachment or with a hand mixer in a large bowl, whip 2 cups of the cream until it holds medium peaks. Beat in ¼ cup of the confectioners' sugar and whip until the cream holds medium-firm peaks. Scrape the cream into a bowl and refrigerate until needed.
Mix the peanut butter and cream cheese. Wipe out (no need to wash) the bowl, fit the stand mixer with the paddle attachment if you have one, or continue with the hand mixer, and beat the cream cheese with the remaining 1 cup confectioners' sugar on medium speed until the cream cheese is satiny smooth. Beat in the peanut butter, ¼ cup of the chopped peanuts and the milk.
Make the peanut butter mousse. Using a large rubber spatula, gently stir in about one quarter of the whipped cream, just to lighten the mousse. Still working with the spatula, stir in the crunchy peanut mixture, then gingerly fold in the remaining whipped cream.
Chill the mousse. Scrape the mousse into the crust, mounding and smoothing the top. Refrigerate for at least 4 hours, or overnight; cover with plastic wrap as soon as the mousse firms.
Melt chocolate. Put 4 oz chopped chocolate in a heatproof bowl and set the bowl over a saucepan of simmering water. Leave the bowl over the water just until the chocolate softens and starts to melt, about 3 minutes; remove the bowl from the saucepan.
Make ganache. Bring the remaining ½ cup cream to a full boil. Pour the cream over the chocolate and, working with a rubber spatula, very gently stir together until the ganache is completely blended and glossy.
Add the ganache to the torte. Pour the ganache over the torte, smoothing it with a metal icing spatula. Scatter the remaining ½ cup peanuts over the top and chill to set the topping, about 20 minutes.
Slice, then serve! When the ganache is firm, remove the sides of the springform pan; it's easiest to warm the pan with a hairdryer, then remove the sides, but you can also wrap a kitchen towel dampened with hot water around the pan and leave it there for 10 seconds. Refrigerate until ready to serve.