Heat the oven to 350 °F and line two baking sheets with parchment paper.
In a large bowl, beat the butter, granulated sugar and brown sugar for 2 minutes, until light and fluffy.
Beat in the egg, orange zest, orange juice and vanilla until smooth.
Add the flour, oats, baking soda and salt to the same bowl and stir until just combined, then fold in the chopped cranberries.
Drop rounded tablespoons of dough about 2 inches apart onto the lined sheets.
Bake 12 to 14 minutes, until the edges are golden and the centers look just set. Cool on the sheets for 5 minutes, then transfer to a wire rack.