In a large bowl, stir together the ricotta, powdered sugar, mascarpone cheese, and vanilla until well combined and smooth.
Using a rubber spatula, fold in the mini chocolate chips.
Transfer the dip into a bowl and top with additional chocolate chips and chopped pistachios. (see note) Cover and refrigerate for 30 minutes or until ready to serve.
Serve chilled with your favorite cookies for dipping.
Notes
You can swap out the pistachios for slivered almonds or your favorite kind of nut.
If you want some extra presentation points, dip the rim of the serving bowl into some melted chocolate and then into chopped pistachios.
You don't have to chill this dip. It's ready to eat as soon as it's mixed, but I think the flavor gets better if you let it sit for a little bit.