Preheat the oven to 350°F.

Break the digestive biscuits into pieces and place them in a food processor. Process until they are crushed into fine crumbs.

Pour the crumbs into a small bowl and add the melted butter and nutmeg. Mix to combine.

Press the crumbs into an 8-inch spring-form pan and bake for approximately 12 to 15 minutes until golden brown.

In a medium-sized bowl, combine the cream cheese, sweetened condensed milk, lemon juice, and vanilla. Mix until very smooth; this can be done by hand or with a mixer.

Peel two of the mandarin oranges and cut each segment into small pieces over the bowl with the cheesecake batter. You want all the juices to fall into the batter. Stir the orange pieces into the batter.

Pour the batter into the crust and spread it out evenly. Cover and refrigerate for at least 8 hours.

Just before serving, peel the last orange and use the segments to decorate the top of the cheesecake.