Neiman Marcus cake is a rich, gooey butter cake with a chewy yellow cake mix crust and a sweet, custardy cream cheese topping. It takes just 15 minutes of prep and serves a crowd, whether you cut it into squares or bite-sized Neiman Marcus bars (makes 12 to 16 squares).
Preheat the oven to 350°F. Lightly grease a 9x13-inch baking pan, then line it with parchment paper, leaving some overhang on the long sides so you can lift the cake out later.
In a large mixing bowl, combine the yellow cake mix, ½ cup melted butter and 2 eggs. Stir until a thick, uniform dough forms with no dry streaks. It will be very thick, more like cookie dough than cake batter.
Press the dough evenly into the bottom of the prepared pan, using lightly greased fingers or the back of a spatula to make a smooth, level layer that reaches the corners.
In a clean mixing bowl, beat the softened cream cheese with a hand mixer on medium speed until smooth and creamy, about 1 minute.
Add the remaining ½ cup melted butter, the remaining 2 eggs and the vanilla, and beat until completely combined and smooth.
Add the sifted powdered sugar about 1 cup at a time, beating on low after each addition, until the topping is smooth and thick.
Pour the cream cheese topping over the crust and spread it gently into an even layer, all the way to the edges of the pan.
Bake for 35 to 40 minutes, until the edges are golden brown and set but the center still has a slight jiggle. Don't overbake; the center firms up as the cake cools.
Set the pan on a wire cooling rack and let the cake cool completely, about 1 hour. For the cleanest slices, refrigerate the cooled cake for 30 to 60 minutes before cutting.
Lift the cake out using the parchment overhang, dust the top lightly with powdered sugar, and cut into 16 squares (or 24 to 32 smaller Neiman Marcus bars). Serve at room temperature or slightly chilled.
Notes
Don't overbake: the soft, gooey center is the whole point. If the entire top is firm when it comes out of the oven, it has baked too long.Cake mix size: most boxes are now 13.25 to 15.25 ounces. Either size works; the crust is just slightly thinner with the smaller box.Room-temperature cream cheese: softened cream cheese blends smoothly and prevents lumps in the topping.Clean cuts: chill the fully cooled cake before slicing, and wipe the knife clean between cuts.Gluten-free: use a gluten-free yellow cake mix and check every label for cross-contact warnings if you're baking for someone with celiac disease.Storage: cover and refrigerate for up to 5 days, or wrap individual pieces and freeze for up to 3 months. Thaw overnight in the refrigerator.