Keep the oven at 350 degrees.
Cream the butter and regular sugar and brown sugar for about 1-3 minutes on medium-high speed in a stand mixer with the beater attachment or with a handheld mixer until the butter resembles mayonnaise.
Add the eggs one at at a time along with the vanilla, orange zest, and orange liquor (if using) and mix on low speed, scraping the bowl to ensure all ingredients are incorporated.
Whisk the all purpose flour, cocoa powder, and salt together in a separate bowl.
Add in the dry ingredients a little at at a time over low speed and mix just until all the ingredients are incorporated, scraping the sides of the bowl occasionally.
Stir in the chocolate chips and hazelnuts until evenly distributed, but don’t over mix. If using a stand mixer, pulse the mixer to barely mix or you can stir them in with a wooden spoon to ensure you don't overmix.
Scoop evenly sized portions onto a parchment-lined baking sheet about four inches apart . The scoops should be about 2 Tbsp. each. You may need to press each scoop together with your hands to ensure the ingredients form together.
Bake at 350 degrees for 8-9 minutes or until the tops of the cookies are just a tad under-baked. They will continue to bake as they sit on the counter. I baked a batch and all of the cookies except for one was baked through after resting for a few minutes, so I just baked that one cookie for 1 extra minute instead of overbaking the entire sheet pan.Baking them less lends a softer gooey cookie and will help them stay moist longer. When in doubt, try one cookie, and if it’s under baked, put it back in the oven for 1-2 minutes. Always SET A TIMER so you don’t over bake your cookies :-)
Store in an airtight container for up to three days. They are best if enjoyed within 24 hours.
This recipe makes about 12 cookies.