Preheat oven to 425°F (220°C). Arrange the tomatoes in a single layer on 3 to 4 parchment-lined baking sheets.

Trim just the tips off each garlic head to expose the cloves, wrap them in foil, and place them on one of the pans.

Roast the tomatoes and garlic in a preheated oven for 40 to 50 minutes, or until the tomato skins split and the garlic is soft. Rotate pans halfway through for even roasting.

Remove the pans and, let cool until the tomatoes and garlic are safe to handle.

Slip the skins off the tomatoes, remove the cores, scoop out the seeds, chop into 1/2-inch chunks, and add to a large saucepot.

Squeeze roasted garlic cloves from skins into a bowl, mash with a fork, and add to the pot.

Add the chopped onions, basil, oregano, parsley, salt, and pepper to the pot.

Bring the mixture to a boil over medium-high heat. Then reduce the heat to medium-low and simmer until it thickens, which should take about 30 to 60 minutes. Stir the mixture often to prevent sticking. Keep it hot while you fill your jars.

Place the water bath canner on the stove and add the rack.

Arrange clean jars upright on the rack.

Fill the canner with water to cover the jars.

Warm over medium heat (180˚F), and simmer for at least 10 minutes. Keep warm as you fill your jars.

Fill a tea kettle or extra pot with water and and place it on the stove.

Lay a clean towel on your work surface.

Use the jar lifter to remove one warm jar from the canner, drain the water back into the pot, and place it on the towel. Keep the remaining jars in the canner so they stay warm.

Remove air bubbles with a bubble popper and adjust headspace if needed.

Wipe the rim of the jar with a clean, damp paper towel to remove any residue. Center a lid on the jar and screw on the band until fingertip tight.

Return the filled jar to the canner and repeat with the remaining jars.

Once the filled jars are back in the canner, adjust the water level so it covers the jars by at least 2 inches. Cover the canner and bring the water to a rolling boil.

Bring your tea kettle or extra pot of water to a boil and keep it boiling in case you need to top off the canner during processing.

Keep the canner covered to maintain the boil and prevent evaporation, but check it frequently to ensure the water level remains at least 1 to 2 inches above the jars.

If additional water is needed, carefully add boiling water around the jars, not directly on top of them, so you don’t disturb the lids or interfere with sealing.

When the processing time is complete, turn off the heat, remove the cover, and let jars rest in the canner for 5 minutes.

Spread a dry kitchen towel on the counter, then use the jar lifter to lift the jars straight up from the canner and transfer them to the towel-lined surface, spacing them a few inches apart.

Don't touch the bands or lids yet. Let the jars sit undisturbed for 12 to 24 hours to cool and seal.

After the jars have cooled for at least 12 hours, check the seals by pressing the center of each lid. If the lid does not pop up, the jar is sealed. Any unsealed jars should be refrigerated and used within a few days.

Remove the screw on bands and wash the jars in warm soapy water to remove any residue, then label and store sealed jars in a cool, dark place. For the best quality and flavor, use within 12 to 18 months.

Store opened jars, and any jars that failed to seal in the refrigerator, and use them within a few days.