In a saucepan, combine the sweetened condensed milk, cocoa powder, and salted butter. Heat over medium-low heat, stirring continuously until melted and well blended.
Allow the fudge mixture to cool slightly. Shape small spoonfuls into flat oval bodies for each mouse.
Dip each strawberry partially into the fudge mixture and place it onto its oval body on a parchment-lined baking tray.
Add roasted peanuts at one end for ears and use colored sprinkles for eyes and other features.
Chill in the refrigerator until set. Serve these delightful treats at your Halloween party!