In a medium bowl, stir graham crumbs, brown sugar, and melted butter until evenly moistened. Press the mixture into the bottom of a 9-inch springform pan using the back of a spoon or a flat-bottom glass. Chill 15 minutes while you make the filling.

In a large bowl or stand mixer, whip the room-temperature cream cheese with sugar and vanilla until smooth—no lumps, no fuss. Scrape down sides to avoid streaks of white.

With the mixer on low, pour in eggnog, then sprinkle in nutmeg and cinnamon. Blend until the mixture is silky and scented like a cup of holiday cocoa.

In a separate chilled bowl, beat the heavy cream until soft peaks form—this makes the filling extra light. Gently fold whipped cream into the cheese mixture, using a spatula and a gentle hand to keep it airy.

Pour the filling over the chilled crust, smoothing the top with an offset spatula. Cover with plastic wrap and refrigerate at least 4 hours, or overnight for a denser slice.

Just before slicing, pipe or dollop whipped cream on top, then dust with a bit of nutmeg or cinnamon. Run a sharp knife under hot water, dry it, and slice—this gives the cleanest cuts.