Preheat oven to 325F; line two 12 cup muffin pans with paper liners and coat with nonstick spray.
Whisk together flour, baking powder, baking soda and salt in a bowl; set aside.
cream sugar and butter in a stand mixer with a paddle attachment on medium speed until white and fluffy; about 5 minutes. Add egg yolks, 1 at a time, beating well after each addition; mix in syrup and vanilla until incorporated. Mix 1/2 the dry ingredients into butter mixture, followed by the buttermilk, then remaining dry ingredients; blend until just incorporated.
Beat whites to stiff peaks in a bowl with a mixer on high speed; fold into batter with coconut and hazelnuts. Fille liners to the top with batter and bake until toothpick inserted in center of a cupcake comes out clean, about 20-25 minutes. Cool cupcakes in pan for about 20 minutes, transfer to a rack, then when completely cool frost with icing.
Whip cream cheese and butter together in a large bowl with a mixer at medium speed until combined. Add syrup and cream, then beat in powdered sugar until creamy. Generously frost each cupcake.