In a large saucepan over medium heat, heat milk, cream, and sugar until just simmering. In a separate bowl, whisk egg yolks. Working fast, whisk 1 tablespoon hot milk mixture into egg yolks. Repeat this method a total of 4 times, whisking egg yolks constantly. Pour egg yolk mixture back into pan, whisking until smooth. Bring mixture to a low simmer until slightly thickened. Remove from heat and whisk in vanilla extract. Cool completely in refrigerator.
Toss cherries with agave and spread on a foil-lined baking sheet. Roast cherries at 400F 15-20 minutes until softened and releasing their juices. Cool completely.
Once ice cream base is cooled, churn ice cream in an ice cream maker according to machine's instruction manual. During last 10 minutes of churning, add roasted cherries (and any juices in pan) and chopped pistachios to ice cream. Once ice cream has finished churning, transfer to a plastic container and freeze until firm, about 2-3 hours.
When ready to serve, scoop ice cream into serving bowls and drizzle with hot fudge sauce. Enjoy!