In a saucepan over medium heat, combine sugar, cocoa powder, and salt. Stir until well mixed.

Add the cubed butter and sweetened condensed milk. Stir continuously until the mixture is smooth and begins to boil.

Remove from heat and stir in vanilla extract.

Line a square baking dish with parchment paper. Pour the fudge mixture into the dish and spread evenly.

Sprinkle chocolate chips, mini marshmallows, and Easter-themed sprinkles on top.

Let the fudge cool at room temperature for about 2 hours, or until set.

Once set, cut the fudge into squares and serve.