Lay a piece of parchment paper inside a loaf pan. Spritz with nonstick cooking spray. Place half of the jelly beans into the bottom of the pan.
Put chocolate chips and condensed milk into a microwave safe bowl. Heat, uncovered, in the microwave for 30 seconds. Stir vigorously, allowing the residual heat to help melt the chocolate.
Add marshmallows to the chocolate and stir to coat. Return the chocolate to the microwave and stir every 15 seconds until melted. Do not overheat the chocolate.
Stir in the vanilla. Pour the fudge over the jelly beans, pressing it down into an even layer between the jelly beans. Press remaining candies into the top of the fudge.
Refrigerate overnight. For best results, bring to room temperature before cutting or use a knife heated with warm water and wiped dry to slice. Cut into squares.