In a small bowl, mix the ricotta with the olives, parsley, pistachios and jalapeño and season with salt and pepper. Lay the mortadella slices on a work surface. Spoon about 2 tablespoons of the ricotta filling slightly below the center of each slice and roll to form tight logs. Refrigerate until chilled.
Trim off the ends and cut each involtini into 3 pieces. Transfer the pieces to a platter cut-side up and serve.
The involtini can be stored in an airtight container for up to 2 days.