Whisk eggs in a large bowl until well combined

Heat milk, cream, and honey in a saucepan until honey dissolves, then cool slightly

Gradually whisk warm milk mixture into eggs to prevent curdling

Add vanilla, salt, and lemon zest, then strain mixture through fine sieve

Pour into greased slow cooker insert or individual ramekins that fit in slow cooker

Cover and cook on low for 2-3 hours until custard is set but still slightly jiggly in center

Cool completely, then refrigerate for at least 2 hours

Serve topped with chopped pistachios and a drizzle of honey