Crush chocolate cookies into fine crumbs using a food processor or a resealable bag and rolling pin. Melt ¼ cup of unsalted butter and mix it into the cookie crumbs until well combined. Firmly press this mixture into the bottom of a 9-inch springform pan, creating an even layer. Set aside while you prepare the filling.

In a large mixing bowl, beat 16 ounces of room-temperature cream cheese and ¾ cup granulated sugar using an electric mixer on medium speed until smooth and creamy, about 2-3 minutes. Add in 3 room-temperature eggs, one at a time, mixing well after each addition. Then, incorporate the zest of one orange, ¼ cup of orange juice, and 1 teaspoon of alcohol-free vanilla extract until fully combined and fluffy.

Melt 1 cup of semi-sweet chocolate chips in a microwave-safe bowl, heating in 30-second intervals and stirring in between until smooth. Allow the melted chocolate to cool slightly before folding it gently into the cream cheese mixture. Ensure the chocolate is evenly distributed throughout, forming a beautifully rich Chocolate Orange Cheesecake filling.

In a small saucepan, dissolve 2 teaspoons of agar-agar powder in ½ cup of water over medium heat. Stir continuously until it has completely dissolved, approximately 3-5 minutes. Allow this mixture to cool slightly before slowly mixing it into the cheesecake filling, ensuring an even consistency and helping the cheesecake to set perfectly.

Pour the creamy filling over the prepared crust in the springform pan. Place it in the oven and bake at 325°F (160°C) for 55-65 minutes. The cheesecake should be set around the edges but slightly jiggly in the center when done. Keep a close eye on it to prevent overbaking, as it will continue to set while cooling.

Once baked, turn off the oven and leave the cheesecake inside with the door slightly ajar for about an hour. This gradual cooling helps reduce the risk of cracking. After an hour, transfer the cheesecake to a wire rack and let it cool completely at room temperature before refrigerating it for at least 4 hours or ideally overnight, allowing the flavors to meld beautifully.