Line a loaf pan or small baking tray, 9" x 4" or similar with foil or parchment paper. Spray the top of the foil or parchment with non-stick cooking spray.
Place each color of candy melt in a separate microwave-safe bowl.
Melt the white candy coating or chocolate chips first, heating for 25 seconds, stirring well, and reheating as needed.
Stir in 3-4 Tablespoons of sweetened condensed milk, to taste (the more milk you use, the softer the final texture). Fold the mixture out into the prepared loaf pan. Use an offset spatula or the back of a spoon to smooth down this layer and place in the fridge.
Repeat steps with the orange candy coating: heating, adding the sweetened condensed milk, and then smoothing over the white fudge layer.
Finish with the yellow candy coating.
Refrigerate for 3 hours or overnight before cutting into squares and serving.