Brown Butter Apple Loaf Cake with Vanilla Filling

Steps

1. Soften the cream cheese at room temperature for 30 minutes, and bring the egg to room temperature.
2. Melt the butter in a small saucepan over medium heat, swirling, until it foams and smells nutty with brown flecks, 4 to 5 minutes. Pour into a large bowl and cool 10 minutes, saving a little to grease the pan.
3. Heat the oven to 350°F (175°C). Grease a 9x5-inch loaf pan with the saved butter and line it with parchment.
4. Make the filling first: in a small bowl, beat the cream cheese with the granulated sugar, the cornstarch and half the vanilla until smooth. Set aside.
5. In a medium bowl, whisk the flour, baking powder, baking soda, salt, cinnamon and nutmeg.
6. Whisk the brown sugar into the cooled browned butter, then whisk in the egg, applesauce and the remaining half of the vanilla until glossy.
7. Fold the flour mixture into the wet mixture just until no dry streaks remain, then fold in the diced apple.
8. Spread half the batter in the pan. Spoon the vanilla filling down the center, leaving a 1/2-inch border, then cover with the remaining half of the batter, sealing the edges.
9. Bake 60 to 70 minutes, tenting with foil after 40 minutes if browning fast, until a toothpick in the cake (not the filling) comes out clean.
10. Cool in the pan 15 minutes, lift out by the parchment, and cool completely on a rack, about 1 1/2 hours, so the filling sets. Cut into 12 slices; refrigerate leftovers.