Let the fudge cool at room temperature for about 15–20 minutes, then transfer the pan to the refrigerator. Chill for at least 2 hours, or until completely firm. For the cleanest cuts, I like to chill it for 3–4 hours or overnight if I’m making it after the kids go to bed.
Once firm, lift the fudge out of the pan using the foil overhang and place it on a cutting board. Peel back the foil and use a sharp knife to cut the fudge into 16 small squares (or smaller bite-size pieces if serving to toddlers). Wipe the knife clean between cuts for neat edges.
Store the fudge in an airtight container in the refrigerator for up to 1 week. For a slightly softer bite for little ones, let the pieces sit at room temperature for 5–10 minutes before serving—though in my house, my toddler usually can’t wait that long after dinner.
For extra cookie flavor, swap the vanilla extract for 1/2 teaspoon of butter extract or use chocolate-filled sandwich cookies instead of classic ones. If you prefer a slightly less sweet fudge, use 2 1/2 cups white chocolate chips and add 2 tablespoons of heavy cream to the bowl before melting to soften the sweetness a bit. For a darker “midnight” look, drizzle melted dark chocolate over the chilled fudge or swirl 1/3 cup melted dark chocolate into the top before it sets. Add a pinch of salt (about 1/8 teaspoon) to the melted mixture for a sweet-salty twist that grown-ups love. To make this more lunchbox-friendly for toddlers, cut the fudge into tiny cubes and keep it very cold so it holds its shape. Around the holidays, mix in a handful of red and green sprinkles with the cookies, or use seasonal sandwich cookie flavors (mint, birthday cake, or pumpkin) to change things up without adding more ingredients. If you don’t have a microwave, you can melt the white chocolate chips and sweetened condensed milk together in a small saucepan over very low heat, stirring constantly, just until smooth—then proceed with the recipe as written.
