Preheat your oven to 350°F. Start by lining an 8-by-8-inch baking pan with aluminum foil, leaving some overhang for easy removal later. Spray the foil with cooking spray to ensure your bars don’t stick.
In a large, microwave-safe bowl, add the butter. Heat on high power for about 1 minute until melted. It should be completely liquid; this will be the base of your crust.
Once melted, add the graham cracker crumbs to the bowl. Using a fork, gently toss the crumbs with the melted butter until they're fully coated. You want a nice, crumbly mixture that’s slightly damp.
Next, pour the crumb mixture into the prepared pan. Using a spatula or your fingertips, press the crumbs firmly into an even layer across the bottom of the pan. It might seem like there isn’t enough, but it’ll work out.
Now, let’s build those layers! Start by evenly sprinkling the white chocolate chips, followed by the semi-sweet chocolate chips. Next, add the chopped walnuts, followed by the dried cranberries and the sweetened shredded coconut flakes. It’s like a beautiful rainbow of ingredients!
Finally, drizzle the sweetened condensed milk over the entire mixture. Make sure to cover everything evenly, as this will help bind the layers together while baking.
Place the pan in the preheated oven and bake for about 20 minutes. Keep a close eye on them, especially in the last few minutes. You want them to be lightly golden brown around the edges.
Once baked, remove the pan from the oven and place it on a wire rack to cool. Allow the bars to cool in the pan for at least 2 hours, or even overnight if you can wait. The bars will firm up as they cool, making them easier to slice.
When you're ready, use the overhanging foil to lift the bars out of the pan. Cut them into squares and serve!
