Preheat oven to 350 degrees. Line baking sheet with parchment or silicone baking mat. Set aside.

In large bowl, stir peanut butter together with sugar, egg and vanilla until combined.

Scoop onto prepared baking sheet using cookie scoop. Bake 10 minutes, until cookies have slightly flattened and are not shiny. Remove from oven and cool 5 minutes on baking sheet.

Press thumb into the center of the warm cookie or use the back of a utensil to create an indentation. Spoon in 1/2 teaspoon nutella into hole and sprinkle with sea salt. Serve.