1. Set a canning rack in a large pot, place four 1-cup jars in the rack, and add water to cover by 1 inch. Bring to a simmer over medium heat, then turn off heat and cover to keep hot.

2. Combine ¼ cup sugar and Sure-Jell in a bowl. Bring blueberries, lemon juice, and lemon zest to simmer in Dutch oven over medium-high heat. Reduce heat to medium-low and simmer, stirring occasionally, until blueberries have softened and released their juice, about 5 minutes.

3. Bring mixture to boil over high heat. Whisk in Sure-Jell mixture and bring to boil. Whisk in remaining 2 1/2 cups sugar and bring to a vigorous boil. Once boiling, cook for 1 minute, whisking constantly. Remove pot from heat and skim any foam from the surface of the jam using a spoon.

4. Place a dish towel flat on the counter. Using a jar lifter, remove jars from the pot, draining water back into the pot. Place jars upside down on a towel and let dry for 1 minute. Using funnel and ladle, portion hot jam into hot jars, leaving ¼ inch headspace at the top of the jars. Slide a wooden skewer along the inside edge of the jar and drag upward to remove air bubbles.

5. For short-term storage: Let jam cool to room temperature, cover, and refrigerate until jam is set, 12 to 24 hours. (Jam can be refrigerated for up to 2 months.)

For long-term storage: While jars are hot, wipe rims clean, add lids, and screw on rings until fingertip-tight; do not over-tighten. Return the pot of water with a canning rack to boil. Lower jars into water, cover, bring water back to boil, then start the timer. Cooking time will depend on your altitude: Boil 10 minutes, then turn off heat and let jars sit in the pot for 5 minutes. Remove jars from pot; let cool for 24 hours. Remove rings, check seal, and clean rims. (Sealed jars can be stored for up to 1 year.)

This recipe was originally found on America’s Test Kitchen but we have modified it for what we found works best for it!