Ingredients:

• 1 medium jalapeño or serrano chile
• 1 cup water
• 1 3/4 cups granulated sugar
• 1 1/2 cups milk
• 1 1/2 cups heavy cream
• 9 large egg yolks
• 1 tablespoon framboise or vanilla extract

Directions:

1. Quarter the chile lengthwise and remove the seeds, veins, and any remnants of stem. Chop it into 1/4−inch pieces. Place the chopped chile in a small saucepan. Add water and 1 cup of the sugar.  Bring to a gentle boil over medium−low heat. Cook for 10 minutes, then remove from the heat and let stand for at least 4 hours.
2. In a medium−size heavy−bottomed saucepan, combine milk, cream and 1 tablespoon of the sugar. Bring to a scald.
3. Meanwhile, put remaining sugar (1/2 cup plus 3 tablespoons), egg yolks and framboise or vanilla extract in a large bowl and whisk just to blend. While gently whisking the yolks, drizzle the hot cream
   mixture into them so that they are gradually warmed up. Return the mixture to the saucepan and set over medium−low heat. Cook, stirring with a wooden spoon and constantly scraping the bottom of the pan, until the custard has thickened slightly and coats the back of the spoon.
4. Strain the custard through a fine sieve into a bowl and nestle it in a larger bowl of ice. Let cool, stirring occasionally, then transfer to an ice cream maker and freeze according to the manufacturer’s instructions.
5. Drain the chile and add to the soft ice cream. Transfer to a storage container and freeze until firm.

I’ve also read that chocolate jalapeno ice cream is popular in some places.