In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, beat the eggs, then add the milk, melted butter, and vanilla extract. Mix until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; the batter should be slightly lumpy.
Preheat your waffle iron according to manufacturer's instructions and lightly grease with non-stick spray or melted butter.
Pour the batter onto the preheated waffle iron, using enough to cover the surface without overflowing.
Close the waffle iron and cook until the waffles are golden brown and crisp, about 3-5 minutes, depending on your waffle iron.
Carefully remove the cooked waffles from the iron and place them on a serving plate.
Spread Nutella hazelnut spread generously over the warm waffles.
If desired, top the Nutella-covered waffles with sliced strawberries or bananas.
Optionally, dust the waffles with powdered sugar for an extra touch of sweetness.
Serve immediately and enjoy!