Stir the crushed Oreo Cookies with the melted butter in a small bowl until the crumbs are evenly moistened, then press the mixture firmly across the bottom of a 9x13-inch baking dish. The crust should look level, dark, and tightly packed with no loose crumb pockets.

Beat the cream cheese and granulated sugar in the bowl of a stand mixer fitted with the whisk attachment until completely smooth, or use a handheld mixer if needed. The mixture should lose all lumps and look thick, pale, and creamy.

Mix in the creamy peanut butter, vanilla extract, and sour cream, scraping the bowl as needed, until the filling base is fully blended. The texture should be dense but silky, with an even peanut butter color throughout.

Pour the cold heavy whipping cream into a separate bowl and begin whipping with a handheld mixer on low speed, then slowly increase to medium speed. It will move from loose bubbles to a thicker, softly billowy texture as air builds.

Fold the whipped cream gently into the peanut butter mixture until no white streaks remain. The finished filling should stay airy and mousse-like rather than flat or runny.

Spread the filling evenly over the prepared crust and refrigerate the pan for at least 5 hours. The surface should look smooth and hold its shape when the filling is fully chilled.

Heat the heavy whipping cream in a microwave-safe bowl for 45 seconds to 1 minute, just until hot. The cream should be steaming but not scorched or boiling over the edges.

Add the milk chocolate chips to the hot cream, let them sit for 5 minutes, then whisk until the ganache is glossy and smooth, about 1 minute. The finished ganache should look shiny and pourable with no unmelted bits.

Pour the ganache over the chilled cheesecake layer, scatter the chopped peanuts on top, and let the topping set for 15 to 20 minutes before cutting and serving. The ganache should look settled and slightly firm so it doesn't drag across the filling when sliced.