To get the One night in Paris achievement, the player has to start a game as 英格兰 (Start date 11 November 1444 in Ironman mode). The achievement is unlocked when the player, as 英格兰 or 大不列颠, owns Paris as a core province.
Start as 英格兰 in 1444. Focus on Admin points so you can core Paris faster. Delete your forts in England to get more money. Build a few mercenaries in Normandy and start moving your other troops to the French mainland. Wait for the Surrender of Maine event to fire and pick the war with France option(It should fire within 3 years of starting the game). Assign Richard Plantagenet to lead your troops and start sieging Paris. In the peace deal take Paris. Use the admin points you stored to core Paris.