Line a baking sheet with parchment paper. Using a 1 teaspoon measuring spoon, place Nutella in small mounds on prepared baking sheet. Place in the freezer for 15 minutes.
Place ¼ cup sugar in a small bowl. In a medium bowl, whisk together flour, baking powder and salt. Line two additional baking sheets with parchment paper. Set all aside.
Preheat oven to 350 defrees. In a large mixing bowl, beat together butter and remaining 1 ½ cups sugar on medium speed until light and fluffy. Beat in eggs, one at a time. Add vanilla and beat to combine. Reduce speed to low and gradually beat in flour mixture until just combined.
Slightly flatten 1 tablespoon dough and sprinkle with a bit of sea salt.
Set on Nutella mound on top. Cover with 1 tablespoon dough, sealing edges. Roll into a ball and roll in set-aside sugar.
Repeat with remaining dough and Nutella. Arrange on prepared baking sheets. Bake for 12 to 15 minutes or until edges are set.
Set pan on wire racks for 10 minutes; then transfer cookies to racks.