(from The Joy of Jams, Jellies, and Other Preserves by Linda Zeidrich)
*Yields about 2 pints or 5 half-pints
2 lbs raspberries
3 cups sugar
2 Tbsp lemon juice
1. In a preserving pan, mash the raspberries with a potato masher. Add sugar and lemon juice. I did a little bit of research, and I guess professional chefs will sometimes warm their sugar in the oven or microwave first to cut down on cooking time since warm things boil more quickly.
2. Over medium heat, heat the mixture, stirring gently, until the sugar is dissolved. Raise the heat to medium-high and boil the mixture, stirring frequently, until either a drop of jam mounds on a chilled dish or the jam "sheets" as it pours off of a chilled spoon. See here for a more complete explanation. The second time I made this jam I boiled it for about 12 minutes, and it was perfect. Keep in mind though that altitude plays a big role, and I live at about 4300 feet above sea level.
3. Ladle the jam into pint or half-pint mason jars, add lids and rings, and process in a boiling water bath for 10 minutes.
4. Be proud of yourself for canning your own, homemade, old-fashioned raspberry jam, and forget about toast or peanutbutter sandwiches--just slather that jam on a brownie a la mode!