Feed it back to her directly

You pull away your mouth. Still pumping her cock with one hand, you point it up into her face and pull down on her head so the head is positioned at the back of her throat. The surprise sends her not just over the edge but flying past it humping at her own face as wave after wave of cum flows down her throat and back out through her lips, tightly stretched around her cock.
As she tastes her own juices for the first time her eyes roll back into her head and she moans deeply for a moment before redoubling her efforts to drink as much of her cum as she can.
Despite her best efforts there is far more than she can hope to swallow. It covers her front and spills out onto the floor. You find yourself a little glad you didn't try to swallow it yourself but after you lick a bit of it from her face you feel like you need to eat up whatever spilled out. It's delicious, like white chocolate, a girly musk that numbs your thought of anything but sex.