1. Preheat the oven to 400 degrees F. Line a large baking sheet with parchment paper and set aside.
2. In a large bowl, whisk together flour, baking powder, sugar, baking soda, and salt. Mix in cold butter with your fingertips until mixture resembles coarse meal. Add buttermilk and stir with a spatula until just combined. With a knife, gently swirl the Nutella into the biscuit dough.
3. Drop round spoonfuls of dough, about three tablespoons, onto prepared baking sheet. Sprinkle biscuits with sea salt, if desired. Bake for 12-15 minutes or until tops are slightly golden brown. Remove from oven, let cool to room temperature and serve.
Note-I updated the recipe to only use 1/2 cup of Nutella. Some readers said that 1 cup of Nutella was too much.