Add the nuts to the bowl of a food processor, fitted with a blade, and pulse until finely ground (it should be powdery and not a paste), about 15 pulses. Set aside. Whisk together the flour, baking powder, cinnamon, and salt in a large bowl until evenly combined and set aside.
Put the butter and sugars in the bowl of a stand mixer, fitted with a paddle attachment, and mix on medium speed until creamy and light, about 2 to 3 minutes. Turn off the mixer, scrape down sides of the bowl, and add egg yolks and vanilla. Mix until well incorporated.
Mix in the orange zest, ground hazelnut powder, and the flour mixture until just incorporated. Divide the dough into 2 even pieces, pat each into a thin disk, enclose in plastic wrap, and let rest in refrigerator at least 1 hour and up to 12 hours.
When ready to bake, preheat the oven to 350 degrees F and arrange racks in the upper and lower third of the oven. Remove the dough from the refrigerator and let sit at room temperature until pliable enough to roll. Roll out half of the dough on a piece of lightly floured parchment or waxed paper to 1/4-inch thickness. Using a 2-inch round cookie or biscuit cutter, cut out rounds of dough. Using a 3/4-inch round cookie cutter, cut out the center of half of rounds to make rings. Transfer rounds and rings to the freezer to set up for 5 minutes before continuing. Gather the dough scraps and chill.
Transfer the chilled cookies to parchment-lined baking sheets, leaving at least 1-inch between each cookie. Bake 2 sheets of cookies at a time until the undersides are golden, switching sheets halfway through, about 12 to 15 minutes total. Cool 5 minutes on sheets then remove to a wire rack to cool completely. Repeat until all dough is used.
To assemble cookies, spread 1 teaspoon of the chocolate spread on the bottom of each solid round cookie, then top with a ring-shaped cookie.
For Blackberry-Pecan Linzer Cookies variation, follow the same instructions except spread 1/2 teaspoon jam on the bottom side of each solid round cookie, then top with a ring-shaped cookie.