The smell of warm, buttery, freshly-baked croissants is synonymous with walking the streets of Paris. Residents never have to worry about heating the warm-from-the-oven croissants passed over the counter at the boulangerie. If you buy a 10-pack of room-temperature croissants from the grocer, or the frozen version, you'll need to figure out how to warm or heat them.
Oven or Toaster Oven
When you don't want to turn on your full-size oven … and you do want to preserve the flaky texture of the croissant, pop a croissant in a toaster oven. Heat for 375 degrees Fahrenheit for 3 minutes if fresh and at room temperature.
If frozen and already baked, heat the croissants for about 7 minutes, first removing them from any wrapping. Monitor them closely, as the frozen ones may be ready in 5 to 10 minutes, depending on size and true temperature of your oven.
If you are heating frozen, unbaked croissants, the time may be closer to 15 minutes after thawing and proofing. For luscious golden-brown tops and bottoms, bake for 5 minutes at 425 F and then lower the oven to 375 F for another 10 to 13 minutes.
The quick and dirty way to heat croissants is to warm them briefly in a microwave, although you will not preserve the desired surface flakiness by using this means. Try 40 seconds on 30 percent power for one large croissant, and 1 minute at 30 percent for two croissants.
Touch the croissant's surface gently to determine if it is nicely warm but not hot, and add 8-second increments if not. Consume the croissants immediately, as letting them sit and cool will dry and harden them.