• NOTE: If you don't strain the jam at all, you'll end up with 4 half-pint jars. If you partially strain the jam, as called for in this recipe, you'll end up with 3 half-pint jars.

Recipe Prep

• Clean three to four 8-ounce jars with hot soapy water (four if you are not straining). Thoroughly rinse the jars with hot water and dry with a clean dish towel.
• Place the blackberries in a colander and spray them with water to gently rinse them. Lay them out on paper towels to absorb some of the moisture.

Combine and Macerate

• In the pot, combine the blackberries, sugar, lemon juice, and cinnamon stick. Gently stir to combine. Let the mixture sit at room temperature for 2 hours, stirring occasionally. This draws the juice out of the berries and dissolves the sugar.

Cook the Jam

• Bring the fruit to a boil over high heat. Once it boils, reduce the heat to medium and cook, stirring occasionally. The fruit should continue to boil. As the jam cooks, foam will rise to the surface. Use a tablespoon to skim off the foam and discard it. This keeps the finished jam clear.
• Cook the jam until it reaches 220°F (104°C), about 25 minutes. Use an instant-read thermometer to check the temperature.
• Once the jam reaches 220°F, remove the pot from the heat and stir in the vanilla extract. Let the jam cool for about 10 minutes, so it’s easier work with especially, if you plan to strain a pprt

Reduce the Seeds (Optional)

• For fewer seeds, set a fine-mesh sieve over a bowl and pour about half the jam through it, pressing the pulp with a spatula to push it through and leave the seeds behind. Discard the seeds and stir the strained jam back into the unstrained half. This cuts the seeds roughly in half while keeping some texture, and gives about 3 jars instead of 4. Skip this step to keep all the seeds and the full yield.
• Stir in Vanilla: Stir the vanilla into the jam off the heat. Adding it off the heat keeps its aroma from cooking off.

Store the Jam

• Let the jam cool for about 10 minutes, then transfer it to the clean jars. Let the jam cool to room temperature, then refrigerate for up to 2-3 weeks.
• Freezing the Jam: If you want to freeze the jam, fill the jars but leave a 1/2-inch headspace. Let the jam cool completely. Refrigerate the jars overnight, then place them in the freezer. Chilling the jars first helps prevent cracking from temperature shock.