Magny-en-Vexin sits where the Vexin plateau tips toward the Epte valley, on a patch of limestone farmland that nobody outside the Paris region thinks about much. That is its charm. The Vexin is a wide, open country of wheat and rapeseed fields, small stone villages and church spires that show up a long way off, and Magny is its market town: a sensible, well-kept place of about five and a half thousand people, with the sort of high street where the baker and the butcher still know each other's business.
As a food stop it does the job without fuss. You will find a boulangerie within a minute of the centre, a few cafés and brasseries with tables out when the weather allows, and a bench or two if you prefer to eat your sandwich in the sun. Lunch in France keeps hours, so try to arrive before one o'clock, or be ready to settle for a baguette and a pastry until the kitchens reopen. Being a real town, it also has fuel, which is the reason to note it on a day that otherwise runs through villages with none.
The roads around here are some of the most relaxed you can find within an hour of Paris. The fields are big and the visibility good, so the lanes between villages are fast and open, with long straights broken by gentle bends and the occasional dip into a wooded valley. In summer the crops stand high at the verges and in spring the rapeseed floods the horizon yellow. The wind can be steady across the plateau, since there is little to stop it, so a tank bag and a tucked-in elbow help.
The Vexin français is a regional nature park, and it is worth knowing that the villages here were built from the local pale stone, which glows in low evening light. Keep an eye out for old washhouses, lime-washed barns and the occasional château behind a wall. Chars and Vigny are the next small settlements on the map if you want somewhere quieter, but for a proper stop with a counter and a till, Magny is the one.