Preheat oven to 175C / 350F. Grease and line a 8 or 9 inch square baking pan with parchment paper.

With a mixer (handheld or stand mixer fitted with the paddle attachment) beat butter for about 1 minute until smooth and creamy. Add in the sugar and beat for 1 minute until combined.

Add the eggs one at a time, beating in between each addition.

Beat in vanilla extract, Nutella and salt until everything is combined.

With the mixer running on low speed, beat in the flour until just combined. Do not overmix the batter.

Pour the batter into the prepared baking pan and bake in the middle of the oven for 30-32 minutes.

Let the brownies cool in the pan for 10-15 minutes before removing and cutting into squares. Garnish with flaky sea salt and serve.