1 envelope unflavored powdered gelatin (about 2½ tsp.)
Extra-virgin olive oil (for pan and drizzling)
2 cups whole-milk fresh ricotta
⅓ cup powdered sugar
½ tsp. vanilla extract
½ tsp. kosher salt
1½ cups half-and-half, divided
2 large or 3 medium nectarines, cut into ½"-thick wedges
Honey (for drizzling)
Pour ¼ cup cold water into a small saucepan and sprinkle gelatin evenly over; let sit 10 minutes to soften.
Meanwhile, coat a 9"-diameter pie or cake pan with a thin film of oil; set aside. Combine ricotta, powdered sugar, vanilla, salt, and 1 cup half-and-half in a food processor.
When gelatin is softened, add remaining ½ cup half-and-half to saucepan and set over low heat. Cook, stirring with a heatproof spatula, until gelatin is completely dissolved (do not let mixture boil). Scrape mixture into food processor and process until completely smooth, about 30 seconds. Pour into prepared pan and chill until set, at least 4 hours (cover loosely with plastic wrap after 1 hour).
Run a butter knife or small offset spatula around sides of panna cotta to loosen the edge and break the suction.