Make the chocolate ganache: Place chocolate chips in a medium heat-proof bowl. Heat the cream in a small saucepan over medium heat until it begins to gently simmer. (Do not let it come to a rapid boil—that’s too hot!) Pour over chocolate, then let it sit for 2–3 minutes to gently soften the chocolate.

With a metal spoon or small silicone spatula, very slowly stir until completely combined and chocolate has melted. If it’s not melting, do not microwave it. Set the ganache aside at room temperature to slightly cool and thicken while you make the pistachio ice cream base.

Make the pistachio ice cream: In a food processor, pulse or process the pistachios until they are finely ground. Set aside.

In a large bowl using a hand mixer or stand mixer fitted with a whisk attachment, whip the heavy cream on medium-high speed until stiff peaks form, about 4 minutes. Add the pistachios, sweetened condensed milk, vanilla extract, almond extract, and green gel food coloring (if using), then beat on low speed until just combined.

Spoon/spread about half of the ice cream mixture into a deep freezer-safe container or bowl. Drop spoonfuls of about half of the chocolate ganache on top. Spoon/spread remaining ice cream mixture on top, followed by remaining ganache. With a knife, gently swirl the ganache and ice cream together. Top with chopped pistachios and chocolate chips, if desired. Cover tightly and freeze for at least 8 hours and up to 2 weeks.

Scoop, serve, and enjoy!