Wash your fresh raspberries and drain them (skip this step if you use frozen raspberries).

Let them rest 2 hours, or ideally overnight covered in the fridge.

Pour the raspberries together with their juice into a large pot and turn on the heat to medium. Keep an eye on it as once they heat up the foam will rise to the top. Lower the heat and mix when that happens.

Simmer at low heat for 1-2 hours or until you get the right consistency. It shouldn't be too watery but also not too thick, as it will thicken once it cools.

While the jam reduces, sterilize your jars and lids in a pot of boiling water for 10 minutes, or using a baby bottle sterilizer.

To test if the jam is ready, place a small amount on a cold plate, let it sit for a minute, then push it with your finger. If it wrinkles, it's set.

Pour the hot jam into the sterilized jars, leaving ¼ of space on top.

For extra precaution, boil the closed jars again for 10 minutes.