1 1/2 cups (450 g) Nutella hazelnut spread
3 eggs (150 g, weighed out of shell) at room temperature, beaten
1 cup (120 g) finely ground blanched almond flour
Preheat your oven to 325°F. Grease and line an 8-inch square baking pan with parchment paper and set it aside.
In a large, heat-safe bowl, place the Nutella and warm it in the microwave or over a simmering pot of water just until it thins out a bit. This will make it easier to beat. Add the eggs, and using a handheld mixer, beat until smooth and fluffy. Add the almond flour and beat again until well-combined. The mixture will be very thickly pourable and very sticky. Transfer the brownie batter to the prepared baking pan and, using a small offset spatula, spread into an even layer. Smack the bottom of the pan a few times on the counter to break any large air bubbles.
Place the baking pan in the center of the preheated oven and bake for 35 to 40 minutes or until the center of the pan of brownies is firm to the touch. Remove from the oven and allow to cool to room temperature in the pan. To make the brownies easier to slice, chill in the refrigerator for about 20 minutes. Remove the brownies from the pan and use a sharp knife to slice into 9 or 12 equal squares. Store any leftover brownies in a sealed container in the refrigerator or freezer.