Bring a medium saucepan of water to a boil. Cut a small x in the bottom of each peach. Doing them one at a time, submerge each peach in the boiling water for 30 seconds, then transfer with a slotted spoon to a bowl of iced water for 1 minute. This will make them easy to peel. Using the slotted spoon, transfer to a bowl large enough to hold all the peaches. Drain the saucepan and set aside.

Peel the peaches with a sharp paring knife, then cut them into eight pieces each, discarding the stones. Finely chop the habanero pepper, using rubber gloves if needed (I did not—I washed my hands thoroughly a couple of times, then applied a little lotion and suffered no burning eyes when I later rubbed my face). As I said above, I included all the seeds and the ribs. Adjust the heat level according to your personal tolerance.

Return the peaches to the saucepan, along with the habanero, tarragon and water. A mere 1/2 cup of water will not seem like much, but as you cook the peaches, they will release plenty of liquid. Bring to a boil, then reduce heat and simmer for 15 to 20 minutes.

Transfer peach mixture to a food processor and purée until completely smooth. Return to pot and add sugar and lemon juice. Cook over low heat, stirring occasionally at first and frequently later to prevent scorching and sticking. Cook for 30 to 40 minutes or longer, until butter reaches desired thickness. One test is dragging a spoon through the butter in the pan; it should leave a trail that closes slowly.

As it cooks, it will bubble and blorp and leave an impressive pattern of spots all over your stove. To avoid this, I partially covered the saucepan and cooked a little longer, about 50 minutes.

Transfer to a glass container and let it cool completely. Cover and refrigerate. The peach butter should keep two weeks or more refrigerated.