Brown Butter Banana Layer Cake with Pastry Cream

Steps

1. Make the pastry cream first so it can chill: in a saucepan, heat the whole milk until steaming. In a bowl, whisk the 2 pastry-cream eggs with half of the granulated sugar, the cornstarch and the 1 g of salt.
2. Slowly whisk the hot milk into the egg mixture, then return it all to the pan. Cook over medium heat, whisking constantly, until thick and bubbling for 1 minute and at least 160°F (71°C).
3. Off the heat, whisk in the 20 g of cubed butter and 5 g of the vanilla. Press plastic wrap onto the surface and refrigerate at least 2 hours, until cold and set.
4. Preheat the oven to 350°F (175°C). Grease and line two 9-inch round pans with parchment.
5. Melt the 170 g of butter in a light-colored pan over medium heat, swirling, until it smells nutty and the solids turn golden brown, 5–7 minutes. Pour into a large bowl and cool 10 minutes.
6. In a separate bowl, whisk the flour, baking soda, baking powder and the 4 g of salt.
7. Whisk the brown sugar and the remaining half of the granulated sugar into the brown butter, then whisk in the 3 cake eggs one at a time, the 400 g of mashed banana, the buttermilk and 10 g of the vanilla.
8. Fold the flour mixture into the banana mixture just until no dry streaks remain. Divide evenly between the pans.
9. Bake 28–32 minutes, until a toothpick in the center comes out clean. Cool in the pans 10 minutes, then turn out onto a rack and cool completely, about 1 hour.
10. Beat the cold heavy cream with the powdered sugar and the remaining 5 g of vanilla to medium-firm peaks.
11. Place one cake layer on a plate. Whisk the chilled pastry cream smooth, spread it over the layer leaving a 1/2-inch border, and arrange the 150 g of sliced banana on top.
12. Set the second layer on top. Spread the whipped cream over the top and sides. Chill 30 minutes to set, then cut into 12 slices. Keep leftovers refrigerated.