A cookie goes stale because moisture leaves it and the starches recrystallize. Everything below is about slowing that down, or reversing it.
Cool completely first
Sealing warm cookies traps steam, the steam condenses, and you wake up to soft, slightly damp cookies with no crisp edge left. Give them a full hour on a rack. I know. Do it anyway.
The bread trick
Put a slice of plain sandwich bread in the container with the cookies. The bread is more porous and gives up its moisture first, so the cookies draw from the bread instead of drying out. In a day the bread goes hard as a cracker and the cookies stay exactly as soft as the day they were baked.
Swap the slice when it goes stiff — usually every couple of days. Use plain white bread; anything seeded or rye will hand its flavor over to the cookies.
Freezing, which is better than you think
Baked cookies freeze beautifully for three months. Cool them fully, stack with parchment between layers, and get as much air out of the bag as you can. Thaw at room temperature for twenty minutes, or go straight to the oven.
Freezing dough is even better. Scoop the balls, freeze them solid on a tray, then bag them. Bake straight from frozen at 325°F, adding two or three minutes. Four warm cookies on a Tuesday night, no bowl to wash. We can't sell you frozen dough — California's cottage food rules keep home kitchens to shelf-stable goods — but nothing stops you doing it in your own freezer.
Bringing them back
- Oven: 350°F for 5–7 minutes. The best result by a wide margin — it re-crisps the edge and re-melts the chocolate.
- Microwave: 10–15 seconds, plus about 20 more if frozen. Fast and soft, but no crisp edge. Fine at midnight.
- Air fryer: 300°F for 3 minutes. Surprisingly good. Watch it closely; the margin is thin.
Don't refrigerate baked cookies
The fridge is the fastest staling environment there is — starch recrystallizes quickest just above freezing. Room temperature or freezer. Never the middle.