Slice the oranges thinly, approximately 1/8 inch thick, removing seeds if needed. A mandolin makes this process move quickly.
In a large saucepan stir together water sugar and vanilla paste.
Add oranges and juice from slicing stirring to combine.
Bring the mixture to a boil.
Reduce heat and simmer, stirring occasionally, until the mixture has thickened to a jammy consistency, about 35-40 minutes.
Transfer the marmalade to jars and seal.
Marmalade can be stored in the refrigerator for up to 10 days in an airtight container.