Line an 8×8 inch square baking pan with parchment paper, ensuring there is a slight overhang on the sides. This “sling” method will make it much easier to lift the fudge out once it has fully set. Lightly grease the parchment paper with a tiny bit of butter or oil to prevent any sticking.
In a large heavy-bottomed saucepan over low heat, combine the chocolate chips and the sweetened condensed milk. Stir constantly with a silicone spatula to ensure the chocolate does not burn at the bottom. Continue heating until the mixture is completely smooth and the chocolate has fully melted into the milk.
Remove the pan from the heat immediately. Sift in the hot cocoa mix powder to avoid lumps, then add the alcohol-free vanilla extract and the sea salt. Stir vigorously until the powder is fully incorporated and the mixture looks glossy and uniform.
Allow the chocolate mixture to cool for about two minutes so it is not piping hot, then gently fold in the mini marshmallows. You want them to be distributed evenly throughout the fudge without melting completely, which creates those lovely white pockets of sweetness.
Pour the mixture into your prepared pan and spread it out evenly with a spatula. Immediately sprinkle the crushed peppermint candies over the top, pressing down very lightly so they adhere to the surface. Place the pan in the refrigerator for at least two to three hours, or until the fudge is firm to the touch.
