Preheat the oven to 325°F. Lightly grease and flour a nine-by-five-inch loaf pan, tapping out any excess flour.
In a glass measuring cup, lightly beat the eggs with the vanilla. In a medium bowl, whisk the 1 1/2 cups of flour with the baking powder and salt.
In a large bowl, using a handheld mixer, beat the butter with the sugar at medium-high speed until fluffy, about three minutes.
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.
Gently mix the Nutella into the pound cake batter. Do not overmix.
Bake the cake for about one hour and 15 minutes, until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 20 minutes. Invert the cake onto a wire rack, turn it right side up, and let it cool completely, about two hours. Cut the cake into slices and serve. Sprinkle with cocoa powder or serve with whipping cream.