Line an 8-inch baking dish with parchment paper. Add 1 cup Campfire® mini fruit-flavored marshmallows into bottom of the prepared baking dish.: The scent of clean parchment and the gentle crinkle as you press it into the dish is the first small joy. Lining the pan prevents sticking and gives clean edges when you lift the set fudge out. Make sure the paper extends over the sides so you can lift the block easily, and smooth any large creases. A common mistake is using too small a sheet, so the fudge adheres to the pan and tears on removal.
In a large microwave-safe bowl, combine the chocolate chips and Nutella. Microwave for 30 seconds and stir to combine. Continue cooking fudge in 30 second increments until the mixture is smooth.: When you layer the bowl with marshmallows they create a springy bed that stops the melted chocolate from seeping all the way to the pan. The marshmallows should glint slightly and sit evenly so the final squares have pockets of soft chew. If you heap them unevenly, the distribution of marshmallow will be lumpy, so spread them gently with your fingers or a small spatula.
Stir in the remaining marshmallows, cocoa crisped rice cereal and dried strawberries.: When you combine the chocolate chips and Nutella you are building the flavor core. The mixture smells deeply chocolatey and nutty, and the Nutella helps the chips melt more smoothly. Use a large bowl so stirring is easy and no hot spots remain. An error here is using a bowl that is too small, which can cause uneven heating and splatter.
Pour melted chocolate and Nutella mixture over the marshmallows in the baking dish. If desired, add festive sprinkles evenly over the fudge. Place fudge into the refrigerator until firm, about 2 hours. Cut into 1-inch squares.: At this stage the chocolate will only be partially melted and the act of stirring begins the emulsification. Stirring distributes heat and helps achieve a glossy finish. Listen for the faint quiet of the chocolate shifting consistency, and stop when you see a mostly homogeneous sheen. Overheating can make the chocolate grainy, so take short bursts and stir between intervals.
Continue cooking fudge in 30 second increments until the mixture is smooth: Patience matters here, because the glossy melt is the difference between a silky fudge and a dull one. Each 30 second burst should be followed by a vigorous stir, scraping the bowl sides so remaining lumps melt from residual heat. The bowl will radiate warmth and the chocolate should flow like thick silk. If it looks separated or oily, reduce microwave time and stir more to coax the emulsion back together.
Stir in the remaining marshmallows cocoa crisped rice cereal and dried strawberries: Once the chocolate is smooth, folding in the remaining marshmallows , cocoa crisped rice cereal , and chopped dried strawberries creates a mosaic of textures. You want even distribution so each square has a bit of everything. Fold gently to keep the cereal crisp and prevent marshmallows from fully dissolving. A typical slipup is over stirring which can deflate the marshmallows and make the mixture uniformly dense.
Pour melted chocolate and Nutella mixture over the marshmallows in the baking dish: Pouring is sensory rich, watch the glossy stream of chocolate pool over the soft bed of marshmallows and then settle. Use a spatula to nudge it into corners and to press it down lightly so there are no air gaps. The surface should look even and shiny. If you press too hard you may compress the marshmallows, losing their airy quality.
If desired add festive sprinkles evenly over the fudge: Sprinkles give a cheerful visual pop and a faint crunch. Scatter them quickly and evenly so they adhere to the warm surface before it cools. If you wait too long the sprinkles will not stick, and if you press them in they may bleed color into the top.
Place fudge into the refrigerator until firm about 2 hours: The fridge hushes the cooling process and firms the chocolate into sliceable bars. After about 2 hours the block should feel solid when you lift the parchment, and the top will lose its glossy wet sheen. Avoid freezing right away as very rapid chilling can cause the chocolate to bloom and lose shine.
Cut into 1 inch squares: I like the tactile satisfaction of slicing clean squares, the knife gliding through the set edge with a soft resistance. For neat cuts warm the knife under hot water and dry it between slices, wiping crumbs away. Cutting too soon leads to smooshed pieces, while waiting too long can make the fudge brittle, so aim for a firm but not rock hard set.