1 and 1/2 cups all purpose flour
4 large eggs, at room temperature
2 teaspoons pure vanilla extract
3/4 teaspoon baking powder
1/4 teaspoon salt
2 sticks unsalted butter, softened
1 and 1/4 cups sugar
one 13ou jar Nutella
1. Preheat oven to 325 degrees. Lightly grease and flour a 9 by 5 inch loaf pan, tapping out excess flour. In a glass measuring cup, lightly beat the eggs with the vanilla. In a medium bowl, whisk the 1 and 1/2 cups of flour with the baking powder and salt.
2. In a large bowl, using a handheld mixer (I used a stand mixer), beat the butter with the sugar at medium high speed until fluffy. With the mixer at medium-low speed, gradually beat in the egg mixture until fully incorporated. Add the flour mixture in three batches, beating at low speed between additions until just incorporated. Continue to beat for 30 seconds longer.
3. Spread 1/3 of the batter in the prepared pan (next time I'd do a little more, the Nutella sinks), then spread the Nutella on top (heat the Nutella in the microwave for 30 seconds before doing this - take the lid off the jar first!). Repeat with another third of the batter and the remaining Nutella. Top with remaining batter. Lightly swirl the Nutella into the batter with a butter knife. Do not overmix.
4. Bake the cake for about one hour and 15 minutes, until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 15 minutes. Invert the cake onto a wrire rack, turn it rightside up and let cool completely, about two hours.