Preheat oven to 350.F. Prepare an 8"-diameter cake pan.
Finely grind the hazelnuts and 1 Tbsp. granulated sugar until finely ground. Set aside 2 Tbsp. of the mixture. Whisk together baking powder, salt, 1 cup flour, and remaining nut mixture in a medium bowl.
In a separate bowl, cream together the butter and remaining granulated sugar.
Beat eggs into the butter one at a time, blending completely between additions.
Thoroughly mix dry ingredients into wet. Scrape batter into pan, and sprinkle with reserved nut mixture and raw sugar.
Bake until cake is golden brown and a tester comes out clean.
Cool in pan on a rack.