Directions

1. Preheat oven to 350 degrees. Butter and flour a 10-inch springform pan; set aside.
2. Place hazelnuts in the bowl of a food processor; process until coarsely chopped and set aside.
3. In a large bowl, whisk together flour, baking powder, and salt; set aside. In the bowl of an electric mixer fitted with the whisk attachment, mix together butter and sugar until light, smooth, and fluffy, scraping down the sides of the bowl as necessary. Add the eggs, olive oil, and orange zest, mixing well on slow speed after each addition.
4. With mixer on low speed, add flour mixture in 3 parts, alternating with milk and beginning and ending with flour; beat until just combined. Scrape down sides of bowl and beat on high speed about 2 minutes; fold in nuts and chocolate.
5. Pour batter into prepared cake pan, smoothing top with a spatula. Bake until a toothpick inserted into the center of the cake comes out clean and the top is light brown and just springs back when lightly touched, about 45 minutes.
6. Transfer cake to a cooling rack; let cool 30 minutes. Remove outer ring of pan; let cool completely. Cut into wedges and serve dusted with confectioners' sugar or whipped cream, if desired.