My tip“Parking fills up early and the road closes when it is full: book your parking online or arrive before 8:30, and avoid weekends.”
The closest real ski resort to Madrid (about an hour away) in the Guadarrama mountains, with excellent organisation and short slopes suited to beginners and children. The season usually runs from December to March, depending on the snow.
Moderate effort, needs a car
On the M-604 road near the Puerto de Cotos pass; limited car parks fill up early at weekends. Cercanías C-9 train to Cotos, then walk. Chains may be needed, and the road closes in storms.
Address
C. Angostura s/n, Valdesquí