In the bottom pot of a double-boiler, bring a few inches of water to a boil, then reduce heat to low to keep water at a simmer. Whisk egg yolks, sugar, orange juice, and zest into the top bowl of double boiler and place on top of bottom pot of simmering water.
Whisk orange curd continuously so the egg yolks don't curdle, Continue whisking orange curd over simmering water until curd becomes smooth and thickened, about 8-10 minutes.
Remove curd from heat and immediately add butter, 1 tablespoon at a time whisking well after each addition. Pour curd into a smaller bowl and press plastic wrap directly to the surface. Chill at least 2 hours.
When ready to serve, use the foil sling to remove cheesecakes from pan to a serving plate. Top each cheesecake with about 1 tablespoon orange curd. Serve immediately and enjoy!